Android Studio 学习（五）网络

HttpURLConnection

OkHttp

• 添加依赖
• 编辑 app/build.gradle 在dependencies闭包中添加
  implementation 'com.squareup.okhttp3:okhttp:3.11.0'

GET

• OkHttpClient client = new OkHttpClient();//创建Client对象
• Request request = new Request.Builder().url("https://www.baidu.com").build();
• Response response = client.newCall(request).execute();//获取返回数据
• String respnseData=response.body().string();//将返回的数据变成string\、

POST

• OkHttpClient client = new OkHttpClient();//创建Client对象
• RequestBody rb= new FormBody.Builder().add("username","admin").build();
• Request request = new Request.Builder().url("https://www.baidu.com").post(rb).build();
• Response response = client.newCall(request).execute();//获取返回数据

使用okhttp发送请求

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

TextView responseText;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    Button button = (Button) findViewById(R.id.button);
    responseText = (TextView) findViewById(R.id.textView);
    button.setOnClickListener(this);
}

@Override
public void onClick(View view) {
    if(view.getId()==R.id.button)
    {
        sendRequestWithOKHttp();
    }
}
private  void  sendRequestWithOKHttp()
{
    new Thread(new Runnable() {
        @Override
        public void run() {
            try{
                OkHttpClient client = new OkHttpClient();
                Request request = new Request.Builder().url("https://www.baidu.com").build();
                Response response = client.newCall(request).execute();
                String respnseData=response.body().string();
                showResponse(respnseData);
            }
            catch (Exception e)
            {
                e.printStackTrace();
            }
        }
    }).start();
}
private void showResponse(final  String response)
{
    runOnUiThread(new Runnable() {
        @Override
        public void run() {
            responseText.setText(response);
        }
    });
}

}

解析XML

Pull解析

private void parseXMLWITHPull (String xmlData)
{
try {
XmlPullParserFactory factory = XmlPullParserFactory.newInstance();//获取实例
XmlPullParser xmlPullParser = factory.newPullParser();
xmlPullParser.setInput(new StringReader(xmlData));//将数据设置进去
int eventType=xmlPullParser.getEventType();//当前解析的事件
String id="";
String name="";
while (eventType!=XmlPullParser.END_DOCUMENT)
{
String nodeName = xmlPullParser.getName();
switch (eventType){
case XmlPullParser.START_TAG:{
if("id".equals(nodeName))
id=xmlPullParser.nextText();
else if ("name".equals(nodeName))
name=xmlPullParser.nextText();
}
break;
case XmlPullParser.END_TAG:
{
if("app".equals(nodeName))
{
Log.d("Main","id is "+id);
Log.d("Main","name is "+name);
}
break;
}
}
eventType=xmlPullParser.next();
}

    } catch (Exception e) {
        e.printStackTrace();
    }
}

解析JSON

JSONObject

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 id = jsonObject.getString("id");
String name = jsonObject.getString("name");
String version = jsonObject.getString("version");
Log.d("Main","id"+id);
Log.d("Main","name"+name);
Log.d("Main","version"+version);
}
}
catch (Exception e)
{
e.printStackTrace();
}
}

GSON

private void parseJSONWithGSON (String jsonData)
{
try{
Gson gson = new Gson();
List appList = gson.fromJson(jsonData,new TypeToken<List>(){}.getType());
for(App app:appList)
{
Log.d("Main","id is"+app.getId());
Log.d("Main","name is"+ app.getName());
Log.d("Main","version is "+ app.getVersion());
}
}
catch (Exception e)
{
e.printStackTrace();
}
}

优化

public class HttpUtil {
public static void sendOkHttpRequest(String address,okhttp3.Callback callback)
{
OkHttpClient client = new OkHttpClient();
Request request = new Request.Builder().url(address).build();
client.newCall(request).enqueue(callback);
}

}
创建这个类
使用时
HttpUtil.sendOkHttpRequest("http://545454/get_data.json",new okhttp3.Callback(){
@Override
public void onResponse(Call call, Response response) throws IOException {
String responseData= response.body().string();
parseJSONWithGSON (responseData);
}

            @Override
            public void onFailure(Call call, IOException e) {

            }
        });