(简单代码)手写Volley

平时常用的能访问网络的框架

Retrofit OkHttp XUtils Volley Afinal Android-async-http.......

平时项目是怎么做的？
UI: 下拉刷新 上拉加载,动画
网络: Retrofit+Rxjava okHttp Volley
数据库: GreenDao Armlite....
图片: Gild.....

使用别人的网络框架会有哪些问题
1.项目中有太多的代码不是我们需要的[本来10M可以写好的App却达到了200M的内存]
2.功能上不满足我们的需求[如Volley不支持大图 大文件 不支持切换线程]

开发一个网络访问框架考虑问题
1.框架的扩展性 不能只处理Json/Xml/image/file/audio/video...
2.框架的易用性 解一个小问题,只需调用一个到两个API
3.框架的稳定性/封装性/异常处理/模块化.........
4.框架和其他框架能否集成(数据库+网络+IOC注入+MVC架构+MVVM架构+资源加载.......)

需求
1.不关心数据解析 获取数据为对象
2.网络访问是在子线程完成 需要实现线程切换 操作可以放生在主线程[对于UI操作]
3.高并发
4.缓存,线程切换,资源价值..............VIP

框架逻辑

逻辑思维

开始撸代码咯~~~~~~~~~~~~~~~~~~~~~~~~~

首先我们先手动加入fastJson包[libs/fastjson-1.2.2.jar]

方法一直接加入依赖:

implementation 'com.alibaba:fastjson:1.2.12'

方法二如图:

fastJson1

fastJson2

然后创建ThreadPoolManage(线程管理类)
在这里我们需要完成以下几点
1.将任务添加到请求队列中 [阻塞式队列]
2.把队列中的任务放入到线程池
3.让他们开始工作起来

//1.将任务添加到请求队列中 [阻塞式队列]
    private LinkedBlockingQueue queue = new LinkedBlockingQueue<>();

    //添加任务
    public void execute(Runnable runnable) {
        if (runnable != null) {
            try {
                queue.put(runnable);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }

    //2.把队列中的任务放入到线程池
    private ThreadPoolExecutor threadPoolExecutor;

    private ThreadPoolManage() {
        threadPoolExecutor = new ThreadPoolExecutor(4, 20, 5, TimeUnit.SECONDS, new ArrayBlockingQueue(4), rejectedExecutionHandler);
        // 开启传送带 让程序跑起来
        threadPoolExecutor.execute(runnable);
    }

    // 拒绝策略
    private RejectedExecutionHandler rejectedExecutionHandler = new RejectedExecutionHandler() {
        @Override
        public void rejectedExecution(Runnable r, ThreadPoolExecutor executor) {
            //参数r就是超时的线程 如果超时就把它重新放回队列里
            try {
                queue.put(r);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    };

    //3.让他们开始工作起来
    private Runnable runnable = new Runnable() {
        @Override
        public void run() {
            while (true) {
                Runnable runnable = null;
                try {
                    //从队列取出请求
                    runnable = queue.take();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                // 取到消息的话 就去执行
                if (runnable != null) {
                    threadPoolExecutor.execute(runnable);
                }
            }
        }
    };

    // 单例
    private static ThreadPoolManage ourInstance = new ThreadPoolManage();
    public static ThreadPoolManage getOurInstance(){
         return ourInstance;
    }

封装请求 [IHttpService ]

public interface IHttpService {
    // 设置网址
    void setUrl(String url);
    // 设置请求参数
    void setRequestData(byte[] requestData);
    // 执行网络操作
    void execute();
    // 需要设置两个接口之间的关联
    void setHttpCallBack(IHttpCallBack httpCallBack);
}

封装响应

public interface IHttpCallBack {
    // 接受上一个接口的结果
    // ----- 成功 -----
    void onSuccess(InputStream inputStream);
    // ----- 失败 -----
    void onFailure();
}

各种任务顶层的类[HttpTask]

public class HttpTask implements Runnable{

    private IHttpService httpService;
    private IHttpCallBack httpCallBack;

    public HttpTask(T requestInfo,String url,IHttpService httpService,IHttpCallBack httpCallBack){
        this.httpService = httpService;
        this.httpCallBack = httpCallBack;
        httpService.setUrl(url);
        // 上一个接口持有下一个接口的引用
        httpService.setHttpCallBack(httpCallBack);
        if (requestInfo != null) {
            // 转换为字符串
            String requsetContent = JSON.toJSONString(requestInfo);
            try {
                // 设置为请求参数 把参数转化为二进制
                httpService.setRequestData(requsetContent.getBytes("utf-8"));
            } catch (UnsupportedEncodingException e) {
                e.printStackTrace();
            }
        }
    }

    @Override
    public void run() {
        httpService.execute();
    }
}

Service实现类 [JsonHttpService]

public class JsonHttpService implements IHttpService{

    private String url;
    private byte[] requestData;
    IHttpCallBack httpCallBack;

    @Override
    public void setUrl(String url) {
        this.url = url;
    }

    @Override
    public void setRequestData(byte[] requestData) {
        this.requestData = requestData;
    }

    @Override
    public void setHttpCallBack(IHttpCallBack httpCallBack) {
        this.httpCallBack = httpCallBack;
    }

    // 真正的网络操作在这里实现
    @Override
    public void execute() {
        httpUrlConnPost();
    }

    HttpURLConnection urlConnection = null;
    public void httpUrlConnPost(){

        URL url = null;

        try {

            url = new URL(this.url);

            urlConnection = (HttpURLConnection) url.openConnection();//打开httpl连接
            urlConnection.setConnectTimeout(6000);//设置连接超时时间
            urlConnection.setUseCaches(false);//不使用缓存
            urlConnection.setInstanceFollowRedirects(true);//是成员函数 仅作用于当初前函数
            urlConnection.setReadTimeout(3000);// 响应的超时时间
            urlConnection.setDoInput(true);// 设置这个连接是否可以写入数据
            urlConnection.setDoOutput(true);// 设置这个连接是否可以输出数据
            urlConnection.setRequestMethod("POST");// 设置请求的方式
            urlConnection.setRequestProperty("Content-Type","application/json;charset");
            urlConnection.connect();//建立连接


            // -------使用字节流发送数据-------
            OutputStream out = urlConnection.getOutputStream();
            BufferedOutputStream bos = new BufferedOutputStream(out);//缓冲字节流包装字节
            if (requestData != null) {
                bos.write(requestData);
            }

            // 把这个字节数组的数据写入缓冲区中
            bos.flush();//刷新缓冲区,发送数据
            out.close();
            bos.close();

            // -------字符流写入数据--------
            if (urlConnection.getResponseCode() == HttpURLConnection.HTTP_OK) {
                InputStream in = urlConnection.getInputStream();
                httpCallBack.onSuccess(in);
            }

        } catch (MalformedURLException e) {
            e.printStackTrace();
            httpCallBack.onFailure();
        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            urlConnection.disconnect(); // 使用完关闭TCP连接,释放资源
        }
    }

}

CallBack实现类 [JsonHttpCallBack]

public class JsonHttpCallBack implements IHttpCallBack {

    // 相应对象的一个字节码
    Class responceClass;
    // 回调数据
    IDataCallBack dataCallBack;

    public JsonHttpCallBack(Class responceClass, IDataCallBack dataCallBack) {
        this.responceClass = responceClass;
        this.dataCallBack = dataCallBack;
    }

    // 用于切换线程
    Handler handler = new Handler(Looper.getMainLooper());

    @Override
    public void onSuccess(InputStream inputStream) {
        // 获取响应结果把byte数据转换成String数据
        String content = getContent(inputStream);
        // 请求结果 ---> Json字符串 ---> 对象
        final M responce = JSON.parseObject(content, responceClass);
        //线程切换
        handler.post(new Runnable() {
            @Override
            public void run() {
                // 把成功结果传输到调用层
                if (dataCallBack != null) {
                    dataCallBack.OnSuccess(responce);
                }
            }
        });
    }

    private String getContent(InputStream inputStream) {
        BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
        StringBuilder sb = new StringBuilder();
        String line = null;
        try {
            while ((line = bufferedReader.readLine()) != null) {
                sb.append(line + "\n");
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                inputStream.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return sb.toString();
    }

    @Override
    public void onFailure(final Exception e) {
        // 线程切换
        //把结果返回给调用层
        handler.post(new Runnable() {
            @Override
            public void run() {
                if (dataCallBack != null) {
                    dataCallBack.onFailure(e);
                }
            }
        });
    }

}

Volly

public class Volly {
    public static void sendJSONRequest(T requsetInfo,String url,Class responce,IDataCallBack dataCallBack){
        IHttpService httpService = new JsonHttpService();
        IHttpCallBack httpCallBack = new JsonHttpCallBack<>(responce,dataCallBack);
        // 拼成任务
        HttpTask httpTask = new HttpTask(requsetInfo,url,httpService,httpCallBack);
        // 执行任务
        ThreadPoolManage.getOurInstance().execute(httpTask);
    }
}

MainActivity

public class MainActivity extends AppCompatActivity {

    private String url = "https://www.wanandroid.com/banner/json";

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

    public void click(View view) {
        Volly.sendJSONRequest(null, url, BannerBean.class, new IDataCallBack() {
            @Override
            public void OnSuccess(BannerBean dataBean) {
                Log.i("OnSuccess", dataBean.getData().toString());
                Toast.makeText(MainActivity.this, "这是什么:是"+dataBean.getData().get(0).getTitle(), Toast.LENGTH_SHORT).show();
            }

            @Override
            public void onFailure(Exception e) {
                Log.i("--->", "onFailure"+e.toString());
            }
        });
    }
}

看一下效果

效果图