Android开发学习之路--网络编程之xml、json
一般网络数据通过http来get，post，那么其中的数据不可能杂乱无章，比如我要post一段数据，肯定是要有一定的格式，协议的。常用的就是xml和json了。在此先要搭建个简单的服务器吧，首先呢下载xampp，然后安装之类的就不再多讲了，参考http://cnbin.github.io/blog/2015/06/05/mac-an-zhuang-he-shi-yong-xampp/。安装好后，启动xampp，之后在浏览器输入localhost或者127.0.0.1就可以看到如下所示了：
这个就表示服务器已经运行了，具体的代码都是放在这个/Applications/XAMPP/htdocs目录下的。然后待会儿编写个xml文件也放在这里。 编写个简单的xml文件吧。
<Person>
2 <Teacher>
3 <name>xiao hong</name>
4 <age>25</age>
5 <sex>woman</sex>
6 <class>english</class>
7 </Teacher>
8 <Student>
9 <name>xiao ming</name>
10 <age>15</age>
11 <sex>man</sex>
12 </Student>
13 </Person>
14
显示的内容就是我们文件的内容，接下去通过app去获取这个信息。
xml解析主要有三种方式，SAX，Pull，Dom。下面就用这几种方法来实现下。
首先是SAX方式，SAX方式主要是两部分组成，一部分是解析器，也就是XMLReader接口，负责读取XML文档，另一部分是事件处理器ContentHandler，负责对发送事件响应和进行XML文档处理。
继承DefaultHandler，并重写5个父类的方法。
1、startDocument方法：开始XML解析的时候调用。
2、startElement方法：开始解析某个节点的时候调用。
3、characters方法：获取节点内容的时候调用。
4、endElement方法：解析完某个节点的时候调用。
5、endDocument方法：完成XML解析时候调用。
先新建类SAXContentHandler类，继承DefaultHandler类，编写代码如下：
package com.jared.emxmlstudy;
import android.util.Log;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;
/**
* Created by jared on 16/2/19.
*/
public class SAXContentHandler extends DefaultHandler {
private static final String TAB = "SAXContentHandler";
private String nodeName;
private StringBuffer mName;
private StringBuffer mAge;
private StringBuffer mSex;
private StringBuffer mClass;
@Override
public void startDocument() throws SAXException {
mName = new StringBuffer();
mAge = new StringBuffer();
mSex = new StringBuffer();
mClass = new StringBuffer();
}
@Override
public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {
nodeName = localName;
}
@Override
public void characters(char[] ch, int start, int length) throws SAXException {
if("name".equals(nodeName)) {
mName.append(ch, start, length);
}else if("age".equals(nodeName)) {
mAge.append(ch, start, length);
} else if("sex".equals(nodeName)) {
mSex.append(ch, start, length);
} else if("class".equals(nodeName)) {
mClass.append(ch, start, length);
}
}
@Override
public void endElement(String uri, String localName, String qName) throws SAXException {
if("Teacher".equals(localName)) {
Log.d(TAB, "This is Teacher");
Log.d(TAB, "name is:" + mName.toString().trim());
Log.d(TAB, "age is:" + mAge.toString().trim());
Log.d(TAB, "sex is:" + mSex.toString().trim());
Log.d(TAB, "class is:" + mClass.toString().trim());
mName.setLength(0);
mAge.setLength(0);
mSex.setLength(0);
mClass.setLength(0);
} else if("Student".equals(localName)) {
Log.d(TAB, "This is Student");
Log.d(TAB, "name is:" + mName.toString().trim());
Log.d(TAB, "age is:" + mAge.toString().trim());
Log.d(TAB, "sex is:" + mSex.toString().trim());
mName.setLength(0);
mAge.setLength(0);
mSex.setLength(0);
}
}
@Override
public void endDocument() throws SAXException {
}
}
这里要使用三种方法，所以修改布局如下：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:layout_margin="10dp"
tools:context="com.jared.emxmlstudy.MainActivity">
<Button
android:id="@+id/getXmlsax"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="SAX方式获取"/>
<Button
android:id="@+id/getXmlpull"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Pull方式获取"/>
<Button
android:id="@+id/getXmldom"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Dom方式获取"/>
</LinearLayout>
然后MainActivity中添加代码如下；
package com.jared.emxmlstudy;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import com.loopj.android.http.AsyncHttpClient;
import com.loopj.android.http.AsyncHttpResponseHandler;
import org.xml.sax.InputSource;
import org.xml.sax.XMLReader;
import java.io.StringReader;
import javax.xml.parsers.SAXParserFactory;
import cz.msebera.android.httpclient.Header;
public class MainActivity extends AppCompatActivity {
private static final String xmlUrl = "http://192.168.1.102/test/person.xml";
private Button mGetXmlSax;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mGetXmlSax = (Button)findViewById(R.id.getXmlsax);
mGetXmlSax.setOnClickListener(new myOnClickListener());
}
private class myOnClickListener implements View.OnClickListener {
@Override
public void onClick(View view) {
switch (view.getId()) {
case R.id.getXmlsax:
sendRequestWithAsyncHttpClient(xmlUrl);
break;
default:
break;
}
}
}
private void sendRequestWithAsyncHttpClient(String url) {
AsyncHttpClient client = new AsyncHttpClient();
client.get(url, new AsyncHttpResponseHandler() {
@Override
public void onSuccess(int i, Header[] headers, byte[] bytes) {
try {
String response = new String(bytes, 0, bytes.length, "utf-8");
parseXMLWithSax(response);
} catch (Exception e) {
e.printStackTrace();
}
}
@Override
public void onFailure(int i, Header[] headers, byte[] bytes, Throwable throwable) {
}
});
}
private void parseXMLWithSax(String xmlData) {
try {
SAXParserFactory factory = SAXParserFactory.newInstance();
XMLReader xmlReader = factory.newSAXParser().getXMLReader();
SAXContentHandler mHandler = new SAXContentHandler();
xmlReader.setContentHandler(mHandler);
xmlReader.parse(new InputSource(new StringReader(xmlData)));
} catch (Exception e) {
e.printStackTrace();
}
}
}
这里用到了AsyncHttpClient，具体库的添加参考上一篇文章Android开发学习之路--网络编程之初体验。好了，这里在发送请求的时候，成功再调用parseXMLWithSax进行解析。这里的地址是192.168.1.102，因为是真机调试，连接到了同一个网段，然后手机就可以访问我们的服务器了。
实例化一个factory，通过XMLReader来读取解析。运行点击按钮如下显示：
02-19 21:01:58.661 17390-17390/? D/SAXContentHandler: This is Teacher 02-19 21:01:58.661 17390-17390/? D/SAXContentHandler: name is:xiao hong 02-19 21:01:58.661 17390-17390/? D/SAXContentHandler: age is:25 02-19 21:01:58.661 17390-17390/? D/SAXContentHandler: sex is:woman 02-19 21:01:58.661 17390-17390/? D/SAXContentHandler: class is:english 02-19 21:01:58.661 17390-17390/? D/SAXContentHandler: This is Student 02-19 21:01:58.661 17390-17390/? D/SAXContentHandler: name is:xiao ming 02-19 21:01:58.661 17390-17390/? D/SAXContentHandler: age is:15 02-19 21:01:58.661 17390-17390/? D/SAXContentHandler: sex is:man
可以发现已经得到我们想要的信息了。
接着使用Pull方式，开始解析可以通过调用它的next方法，获取下一个事件，可以通过getAttribute方法获取属性，通过nextText方法来获取节点的值。编写代码如下：
package com.jared.emxmlstudy;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import com.loopj.android.http.AsyncHttpClient;
import com.loopj.android.http.AsyncHttpResponseHandler;
import org.xml.sax.InputSource;
import org.xml.sax.XMLReader;
import org.xmlpull.v1.XmlPullParser;
import org.xmlpull.v1.XmlPullParserFactory;
import java.io.StringReader;
import javax.xml.parsers.SAXParserFactory;
import cz.msebera.android.httpclient.Header;
public class MainActivity extends AppCompatActivity {
private static final String TAB = "XMLParse";
private static final String xmlUrl = "http://192.168.1.102/test/person.xml";
private Button mGetXmlSax;
private Button mGetXmlPull;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mGetXmlSax = (Button)findViewById(R.id.getXmlsax);
mGetXmlPull = (Button)findViewById(R.id.getXmlpull);
mGetXmlSax.setOnClickListener(new myOnClickListener());
mGetXmlPull.setOnClickListener(new myOnClickListener());
}
private class myOnClickListener implements View.OnClickListener {
@Override
public void onClick(View view) {
switch (view.getId()) {
case R.id.getXmlsax:
sendRequestWithSax(xmlUrl);
break;
case R.id.getXmlpull:
sendRequestWithPull(xmlUrl);
break;
default:
break;
}
}
}
private void sendRequestWithPull(String url) {
AsyncHttpClient client = new AsyncHttpClient();
client.get(url, new AsyncHttpResponseHandler() {
@Override
public void onSuccess(int i, Header[] headers, byte[] bytes) {
try {
String response = new String(bytes, 0, bytes.length, "utf-8");
parseXMLWithPull(response);
} catch (Exception e) {
e.printStackTrace();
}
}
@Override
public void onFailure(int i, Header[] headers, byte[] bytes, Throwable throwable) {
}
});
}
private void parseXMLWithPull(String xmlData) {
try {
XmlPullParserFactory factory = XmlPullParserFactory.newInstance();
XmlPullParser xmlPullParser = factory.newPullParser();
xmlPullParser.setInput(new StringReader(xmlData));
int eventType = xmlPullParser.getEventType();
String mName = "";
String mAge = "";
String mSex = "";
String mClass = "";
while (eventType != XmlPullParser.END_DOCUMENT) {
String nodeName = xmlPullParser.getName();
switch (eventType) {
case XmlPullParser.START_TAG: {
if("name".equals(nodeName)) {
mName = xmlPullParser.nextText();
} else if("age".equals(nodeName)) {
mAge = xmlPullParser.nextText();
} else if("sex".equals(nodeName)) {
mSex = xmlPullParser.nextText();
} else if("class".equals(nodeName)) {
mClass = xmlPullParser.nextText();
}
break;
}
case XmlPullParser.END_TAG: {
if("Teacher".equals(nodeName)) {
Log.d(TAB, "This is Teacher");
Log.d(TAB, "name is:" + mName.trim());
Log.d(TAB, "age is:" + mAge.trim());
Log.d(TAB, "sex is:" + mSex.trim());
Log.d(TAB, "class is:" + mClass.trim());
} else if("Student".equals(nodeName)) {
Log.d(TAB, "This is Student");
Log.d(TAB, "name is:" + mName.trim());
Log.d(TAB, "age is:" + mAge.trim());
Log.d(TAB, "sex is:" + mSex.trim());
}
}
default:
break;
}
eventType = xmlPullParser.next();
}
} catch (Exception e) {
e.printStackTrace();
}
}
private void sendRequestWithSax(String url) {
AsyncHttpClient client = new AsyncHttpClient();
client.get(url, new AsyncHttpResponseHandler() {
@Override
public void onSuccess(int i, Header[] headers, byte[] bytes) {
try {
String response = new String(bytes, 0, bytes.length, "utf-8");
parseXMLWithSax(response);
} catch (Exception e) {
e.printStackTrace();
}
}
@Override
public void onFailure(int i, Header[] headers, byte[] bytes, Throwable throwable) {
}
});
}
private void parseXMLWithSax(String xmlData) {
try {
SAXParserFactory factory = SAXParserFactory.newInstance();
XMLReader xmlReader = factory.newSAXParser().getXMLReader();
SAXContentHandler mHandler = new SAXContentHandler();
xmlReader.setContentHandler(mHandler);
xmlReader.parse(new InputSource(new StringReader(xmlData)));
} catch (Exception e) {
e.printStackTrace();
}
}
}
运行结果如下：
02-19 21:52:01.391 19388-19388/? D/XMLParse: This is Teacher 02-19 21:52:01.391 19388-19388/? D/XMLParse: name is:xiao hong 02-19 21:52:01.391 19388-19388/? D/XMLParse: age is:25 02-19 21:52:01.391 19388-19388/? D/XMLParse: sex is:woman 02-19 21:52:01.391 19388-19388/? D/XMLParse: class is:english 02-19 21:52:01.391 19388-19388/? D/XMLParse: This is Student 02-19 21:52:01.391 19388-19388/? D/XMLParse: name is:xiao ming 02-19 21:52:01.391 19388-19388/? D/XMLParse: age is:15 02-19 21:52:01.391 19388-19388/? D/XMLParse: sex is:man
最后一种是Dom方式，Dom方式主要比较耗费内存，需要遍历所有，一般手机上的app开发不太适用。那就简单实现下吧，还是利用Async-HttpClient，接着编写代码如下：
private void parseXMLWithDom(String xmlData) {
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
String mName = "";
String mAge = "";
String mSex = "";
String mClass = "";
try {
DocumentBuilder builder = factory.newDocumentBuilder();
//Document document = builder.parse(xmlData);
Document document = builder.parse(new InputSource(new StringReader(xmlData)));
Element root = document.getDocumentElement();
Log.d(TAB, "根节点名称：" + root.getTagName());
NodeList items = root.getElementsByTagName("Teacher");
Element personElement = (Element)items.item(0);
Log.d(TAB, "根节点名称：" + personElement.getTagName());
NodeList childNodes = personElement.getChildNodes();
Log.d(TAB, "This is Teacher");
for(int i = 0; i < childNodes.getLength(); i++) {
Node grandElement = childNodes.item(i);
if(grandElement.getNodeType() == Node.ELEMENT_NODE) {
if("name".equals(grandElement.getNodeName())) {
mName = grandElement.getFirstChild().getNodeValue();
Log.d(TAB, "name is:" + mName.trim());
} else if("age".equals(grandElement.getNodeName())) {
mAge = grandElement.getFirstChild().getNodeValue();
Log.d(TAB, "age is:" + mAge.trim());
} else if("sex".equals(grandElement.getNodeName())) {
mSex = grandElement.getFirstChild().getNodeValue();
Log.d(TAB, "sex is:" + mSex.trim());
} else if("class".equals(grandElement.getNodeName())) {
mClass = grandElement.getFirstChild().getNodeValue();
Log.d(TAB, "class is:" + mClass.trim());
}
}
}
} catch (Exception e){
e.printStackTrace();
}
}
这里简单的就实现了Teacher的，student的就没有添加，相信也是很容易的了，其余的代码和上述类似，运行效果如下：
02-20 09:16:49.601 1353-1353/? D/XMLParse: 根节点名称：Person 02-20 09:16:49.601 1353-1353/? D/XMLParse: 根节点名称：Teacher 02-20 09:16:49.601 1353-1353/? D/XMLParse: This is Teacher:9 02-20 09:16:49.601 1353-1353/? D/XMLParse: name is:xiao hong 02-20 09:16:49.601 1353-1353/? D/XMLParse: age is:25 02-20 09:16:49.601 1353-1353/? D/XMLParse: sex is:woman 02-20 09:16:49.601 1353-1353/? D/XMLParse: class is:english
关于xml基本上先学习这些知识了。接着学习json的知识。
首先和xml一样，新建一个person.json文件，如下：
1 [{"name":"xiao hong", "age":"25", "sex":"wonan"},
2 {"name":"xiao ming", "age":"15", "sex":"man"},
3 {"name":"xiao qiang", "age": 30, "sex":"man"}]
保存到和xml同一级目录下，运行浏览器如下图所示：
如图可知配置已经ok了，那么接下来就开始完成代码了，这里要使用JSONObject和GSON来实现，布局如下：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:layout_margin="10dp"
tools:context="com.jared.emjsonstudy.MainActivity">
<Button
android:id="@+id/getJSONObject"
android:text="Get Json With JSONObject"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textAllCaps="false"/>
<Button
android:id="@+id/getGSON"
android:text="Get Json With GSON"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textAllCaps="false"/>
</LinearLayout>
接着实现代码，还是用了Async-HttpClient来实现，代码如下：
package com.jared.emjsonstudy;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import com.loopj.android.http.AsyncHttpClient;
import com.loopj.android.http.AsyncHttpResponseHandler;
import org.json.JSONArray;
import org.json.JSONObject;
import cz.msebera.android.httpclient.Header;
public class MainActivity extends AppCompatActivity {
private static final String TAB = "JSONStudy";
private static final String JSON_URL = "http://192.168.1.102/test/person.json";
private Button mGetJSONObjectBtn;
private Button mGetGSONBtn;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mGetJSONObjectBtn = (Button)findViewById(R.id.getJSONObject);
mGetGSONBtn = (Button)findViewById(R.id.getGSON);
mGetJSONObjectBtn.setOnClickListener(new myOnClickListener());
mGetGSONBtn.setOnClickListener(new myOnClickListener());
}
private class myOnClickListener implements View.OnClickListener {
@Override
public void onClick(View view) {
switch (view.getId()) {
case R.id.getJSONObject:
getJSONWithJSONObject(JSON_URL);
break;
case R.id.getGSON:
break;
default:
break;
}
}
}
private void parseJSONWithJSONObject(String jsonData) {
try {
JSONArray jsonArray = new JSONArray(jsonData);
for (int i = 0; i < jsonArray.length(); i++) {
JSONObject jsonObject = jsonArray.getJSONObject(i);
String mName = jsonObject.getString("name");
String mAge = jsonObject.getString("age");
String mSex = jsonObject.getString("sex");
Log.d(TAB, "name is: " + mName);
Log.d(TAB, "age is: " + mAge);
Log.d(TAB, "sex is:" + mSex);
}
} catch (Exception e) {
e.printStackTrace();
}
}
private void getJSONWithJSONObject(String url) {
AsyncHttpClient client = new AsyncHttpClient();
client.get(url, new AsyncHttpResponseHandler() {
@Override
public void onSuccess(int i, Header[] headers, byte[] bytes) {
try {
String response = new String(bytes, 0, bytes.length, "utf-8");
parseJSONWithJSONObject(response);
} catch (Exception e) {
e.printStackTrace();
}
}
@Override
public void onFailure(int i, Header[] headers, byte[] bytes, Throwable throwable) {
}
});
}
}
如上代码明显比xml的简单多了，JSONArray获取到Json数据，然后通过JSONObject来获取对应键值的内容。因为我的电脑ip地址是192.168.1.102，手机和电脑在同一个网段，所以直接利用真机来测试，效果如下：
02-20 10:13:20.521 4947-4947/? D/JSONStudy: name is: xiao hong 02-20 10:13:20.521 4947-4947/? D/JSONStudy: age is: 25 02-20 10:13:20.521 4947-4947/? D/JSONStudy: sex is:wonan 02-20 10:13:20.521 4947-4947/? D/JSONStudy: name is: xiao ming 02-20 10:13:20.521 4947-4947/? D/JSONStudy: age is: 15 02-20 10:13:20.521 4947-4947/? D/JSONStudy: sex is:man 02-20 10:13:20.521 4947-4947/? D/JSONStudy: name is: xiao qiang 02-20 10:13:20.521 4947-4947/? D/JSONStudy: age is: 30 02-20 10:13:20.521 4947-4947/? D/JSONStudy: sex is:man
接着使用google的开源库GSON来实现，用到开源库，那就先下载了。gson下载地址：GSON下载地址点击这里。gson gitbub地址：https://github.com/google/gson。
GSON库主要是将一段JSON格式的字符串自动映射成一个对象，从而不需要编写代码去解析。这里新建一个Person类来获取数据，代码如下：
package com.jared.emjsonstudy;
/**
* Created by jared on 16/2/20.
*/
public class Person {
private String name;
private String age;
private String sex;
public String getName() {
return name;
}
public String getAge() {
return age;
}
public String getSex() {
return sex;
}
public void setName(String name) {
this.name = name;
}
public void setAge(String age) {
this.age = age;
}
public void setSex(String sex) {
this.sex = sex;
}
}
MainActivity中添加代码：
void parseJSONWithGSON(String jsonData) {
Gson gson = new Gson();
List<Person> personList = gson.fromJson(jsonData,
new TypeToken<List<Person>>(){}.getType());
for (Person person :personList) {
Log.d(TAB, "Gson: name is: " + person.getName());
Log.d(TAB, "Gson: age is: " + person.getAge());
Log.d(TAB, "Gson: sex is:" + person.getSex());
}
}
void getJSONWithGSON(String url) {
AsyncHttpClient client = new AsyncHttpClient();
client.get(url, new AsyncHttpResponseHandler() {
@Override
public void onSuccess(int i, Header[] headers, byte[] bytes) {
try {
String response = new String(bytes, 0, bytes.length, "utf-8");
parseJSONWithGSON(response);
} catch (Exception e) {
e.printStackTrace();
}
}
@Override
public void onFailure(int i, Header[] headers, byte[] bytes, Throwable throwable) {
}
});
}这里new了一个Gson，然后通过fromJson的方法，通过TypeToken获取数据并保存到Person列表中。运行看下效果：
02-20 10:42:56.381 6434-6434/? D/JSONStudy: Gson: name is: xiao hong 02-20 10:42:56.381 6434-6434/? D/JSONStudy: Gson: age is: 25 02-20 10:42:56.381 6434-6434/? D/JSONStudy: Gson: sex is:wonan 02-20 10:42:56.381 6434-6434/? D/JSONStudy: Gson: name is: xiao ming 02-20 10:42:56.381 6434-6434/? D/JSONStudy: Gson: age is: 15 02-20 10:42:56.381 6434-6434/? D/JSONStudy: Gson: sex is:man 02-20 10:42:56.381 6434-6434/? D/JSONStudy: Gson: name is: xiao qiang 02-20 10:42:56.381 6434-6434/? D/JSONStudy: Gson: age is: 30 02-20 10:42:56.381 6434-6434/? D/JSONStudy: Gson: sex is:man当然如果想要生存json数据，也是可以用gson的tojson方法的。
