43. RX思维的魅力

43.1 在下载图片的前提下增加需求

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加水印需求

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现在的完整代码：

package com.dingjiaxiong.myrxjava;

import androidx.appcompat.app.AppCompatActivity;

import android.app.ProgressDialog;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.ImageView;

import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;

import io.reactivex.rxjava3.android.schedulers.AndroidSchedulers;
import io.reactivex.rxjava3.annotations.NonNull;
import io.reactivex.rxjava3.core.Observable;
import io.reactivex.rxjava3.core.Observer;
import io.reactivex.rxjava3.disposables.Disposable;
import io.reactivex.rxjava3.functions.Consumer;
import io.reactivex.rxjava3.functions.Function;
import io.reactivex.rxjava3.schedulers.Schedulers;

public class MainActivity extends AppCompatActivity {

// 打印logcat日志的标签
private final String TAG = MainActivity.class.getSimpleName();

// 网络图片的链接地址
private final static String PATH = "http://pcsource.upupoo.com/theme/2000858833/previewFix.jpg";

// 弹出加载框（正在加载中...）
private ProgressDialog progressDialog;

// ImageView控件，用来显示结果图像
private ImageView image;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

image = findViewById(R.id.image);
}

/**
* 图片显示加载功能
*
* @param view
*/
public void showImageAction(View view) {

//如果采用传统开发方式，后面的开发者接手前面开发者的代码，就很痛苦（弊端）
/**
* TODO　RX思维
*
* 起点和终点
*
* RxJava RXJS RxXXX RX系列框架为什么把所有函数都成为操作符因为我们的函数要去操作从起点流向终点7
*
*/

// 起点
Observable.just(PATH)

// 需求：001 图片下载需求 PATH ---》 Bitmap
.map(new Function<String, Bitmap>() {
@NonNull
@Override
public Bitmap apply(@NonNull String path) throws Exception {
try {
Thread.sleep(2000); // 睡眠2秒钟

URL url = new URL(path);
HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
httpURLConnection.setConnectTimeout(5000); // 设置请求连接时长 5秒
int responseCode = httpURLConnection.getResponseCode(); // 才开始 request 拿到服务器的响应 200成功 404有问题 ...
if (responseCode == HttpURLConnection.HTTP_OK) {
InputStream inputStream = httpURLConnection.getInputStream();
Bitmap bitmap = BitmapFactory.decodeStream(inputStream);
return bitmap;
}
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
})

//需求 2 加水印
.map(new Function<Bitmap, Bitmap>() {
@Override
public Bitmap apply(Bitmap bitmap) throws Throwable {
Paint paint = new Paint();
paint.setColor(Color.RED);
paint.setTextSize(88);
Bitmap bitmap_withShuiyin = drawTextToBitmap(bitmap, "DingJiaxiong学Android！", paint, 88, 88);

return bitmap_withShuiyin;
}
})

// 给上面的分配异步线程（图片下载操作）
.subscribeOn(Schedulers.io())

// 终点分配 Android主线程
.observeOn(AndroidSchedulers.mainThread())

// 关联：观察者设计模式关联起点和终点 == 订阅
.subscribe(

// 终点
new Observer<Bitmap>() {

// 订阅成功
@Override
public void onSubscribe(Disposable d) {
progressDialog = new ProgressDialog(MainActivity.this);
progressDialog.setTitle("RXjava Dingjiaxiong running...");
progressDialog.show();
}

// 上一层给我的响应
@Override
public void onNext(Bitmap bitmap) {
image.setImageBitmap(bitmap); // 显示到控件上
}

// 链条思维发生了异常
@Override
public void onError(Throwable e) {

}

// 整个链条全部结束
@Override
public void onComplete() {
if(progressDialog != null){
progressDialog.dismiss();
}
}
});

}

// 图片上绘制文字、加水印
private final Bitmap drawTextToBitmap(Bitmap bitmap, String text, Paint paint, int paddingLeft, int paddingTop) {
Bitmap.Config bitmapConfig = bitmap.getConfig();

paint.setDither(true); // 获取跟清晰的图像采样
paint.setFilterBitmap(true);// 过滤一些
if (bitmapConfig == null) {
bitmapConfig = Bitmap.Config.ARGB_8888;
}
bitmap = bitmap.copy(bitmapConfig, true);
Canvas canvas = new Canvas(bitmap);

canvas.drawText(text, paddingLeft, paddingTop, paint);
return bitmap;
}

}

运行

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奈斯

再加个需求，记录日志

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// 需求 3 日志记录
.map(new Function<Bitmap, Bitmap>() {
@NonNull
@Override
public Bitmap apply(@NonNull Bitmap bitmap) throws Throwable {
Date day=new Date();
SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
System.out.println("下载时间" + df.format(day));
return bitmap;
}
})

运行

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妙啊

43.2 还有很多其他的操作符

这里贴上另一位博主的帖子：https://blog.csdn.net/chuyouyinghe/article/details/122806097

举个栗子

再加上一个按钮

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public void action(View view) {
String[] strings = {"AAA","BBB","CCC"};
//起点
Observable.fromArray(strings)

//订阅：起点和终点
.subscribe(new Consumer<String>() {
@Override
public void accept(String s) throws Throwable {
System.out.println(s);
}
});
}

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43.3 自定义Observer解决问题
如果登陆成功，只想拿到成功Bean == SuccessBean

如果登录失败，只想拿到 message string 类型

总Bean和成功Bean

ResponseResult.java

package com.dingjiaxiong.myrxjava.login.bean;

// 请求服务器的结果Bean 总Bean
public class ResponseResult {

// 登录成功
private SuccessBean data; // 成功Bean
private int code;
private String message;

public ResponseResult(SuccessBean data, int code, String message) {
this.data = data;
this.code = code;
this.message = message;
}

public ResponseResult() {
}

public SuccessBean getData() {
return data;
}

public void setData(SuccessBean data) {
this.data = data;
}

public int getCode() {
return code;
}

public void setCode(int code) {
this.code = code;
}

public String getMessage() {
return message;
}

public void setMessage(String message) {
this.message = message;
}

@Override
public String toString() {
return "ResponseResult{" +
"data=" + data +
", code=" + code +
", message='" + message + '\'' +
'}';
}
}

SuccessBean.java

package com.dingjiaxiong.myrxjava.login.bean;

// 登录注册成功的 Bean 信息
public class SuccessBean {

private int id;
private String name;

public SuccessBean() {
}

public SuccessBean(int id, String name) {
this.id = id;
this.name = name;
}

public int getId() {
return id;
}

public void setId(int id) {
this.id = id;
}

public String getName() {
return name;
}

public void setName(String name) {
this.name = name;
}

@Override
public String toString() {
return "SuccessBean{" +
"id=" + id +
", name='" + name + '\'' +
'}';
}
}

定义登录引擎

LoginEngine.java

package com.dingjiaxiong.myrxjava.login.core;

import com.dingjiaxiong.myrxjava.login.bean.ResponseResult;
import com.dingjiaxiong.myrxjava.login.bean.SuccessBean;

import io.reactivex.rxjava3.core.Observable;
import okhttp3.Response;

public class LoginEngine {

// 返回起点
public static Observable<ResponseResult> login(String name, String pwd) {

// 最终返回总Bean
ResponseResult responseResult = new ResponseResult();

if ("dingjiaxiong".equals(name) && "123".equals(pwd)) { // 登录成功

// 创建成功 Bean
SuccessBean successBean = new SuccessBean();
successBean.setId(45674565);
successBean.setName("Dingjiaxiong 登录成功");

/**
* {
* data:{ xxxxxxx 登录成功的Bean xxxxxxx SuccesBean 成功Bean }
* code:200
* message:"登录成功"
* }
*/
responseResult.setData(successBean);
responseResult.setCode(200);
responseResult.setMessage("登录成功");

} else { // 登录失败

/**
* {
* data:null
* code:404
* message:"登录错误"
* }
*/
responseResult.setData(null);
responseResult.setCode(404);
responseResult.setMessage("登录错误");
}

// 起点
return Observable.just(responseResult);
}

}

new 一个新的Activity

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创建自己的observer

package com.dingjiaxiong.myrxjava.login.core;

import com.dingjiaxiong.myrxjava.login.bean.ResponseResult;
import com.dingjiaxiong.myrxjava.login.bean.SuccessBean;

import io.reactivex.rxjava3.core.Observer;
import io.reactivex.rxjava3.disposables.Disposable;

public abstract class CustomObserver implements Observer<ResponseResult> {

public abstract void success(SuccessBean successBean);
public abstract void error(String message);

@Override
public void onSubscribe(Disposable d) {

}

@Override
public void onNext(ResponseResult responseResult) {
if (responseResult.getData() == null) {
error(responseResult.getMessage() + "请求失败");
} else {
success(responseResult.getData());
}
}

@Override
public void onError(Throwable e) {
error(e.getMessage() + "错误详情");
}

@Override
public void onComplete() {

}
}

调用登录操作

LoginEngine.login("dingjiaxiong", "123")
//返回起点
.subscribe(new CustomObserver() {
@Override
public void success(SuccessBean successBean) {
System.out.println("dingjiaxiong" + "登录成功" + successBean.toString());
}

@Override
public void error(String message) {
System.out.println("登录失败" + message);
}
});

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