LG工具类Util的使用(一)

工具类Util的使用
package utils;

import android.content.Context;
import android.net.ConnectivityManager;
import android.net.Network;
import android.os.AsyncTask;

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

/**

• 网络请求工具类：
• 1.使用单利模式，保证项目中只有这一个实例，减少内存消耗，提高运行效率
  */

public class HttpUtils {
public static final String ERROR1 = “网络加载失败”;
public static final String ERROR2 = “有异常”;
//单利模式-饿汉式
private static HttpUtils httpUtils = new HttpUtils();
private HttpLoadListener httpLoadListener;

private HttpUtils() {
}

public static HttpUtils getHttpUtils() {
    if (httpUtils == null) {
        httpUtils = new HttpUtils();
    }
    return httpUtils;
}

//封装，在这里调用AsncTask方法
public void get(String url) {
    MyTask myTask = new MyTask();
    myTask.execute(url);//传入url地址
}

//使用AsyncTask
class MyTask extends AsyncTask<String, Void, String> {
    //        doInBackground 在后台线程执行的方法
    @Override
    protected String doInBackground(String... strings) {
        //在子线程 进行网络请求
        String url1 = strings[0];

        try {
            URL u = new URL(url1);
            HttpURLConnection con = (HttpURLConnection) u.openConnection();
            con.setConnectTimeout(5000);
            if (con.getResponseCode() == 200) {
                InputStream is = con.getInputStream();
                //将流转成---json
                String json = inputStream2String(is);
                return json;
            } else {
                return ERROR1;
            }

        } catch (IOException e) {
            e.printStackTrace();
            return ERROR2;
        }
    }

    //在主线程处理回调
    @Override
    protected void onPostExecute(String s) {
        super.onPostExecute(s);
        switch (s) {
            case ERROR1:

// 加载失败
httpLoadListener.loadError(ERROR1);
break;
case ERROR2:
httpLoadListener.loadError(ERROR2);

                break;
            default:

// 加载成功
httpLoadListener.loadError(s);
break;
}
}
}

//定义接口
public interface HttpLoadListener {
    //        接口里面成功失败的回调方法的定义
    void loadSuccess(String json);

    void loadError(String error);
}

//对外部提供的设置监听的方法
public void setOnHttpLoadListener(HttpLoadListener httpLoadListener) {
    this.httpLoadListener = httpLoadListener;
}

//判断网络状态
public boolean hasNet(Context context) {
    ConnectivityManager cm = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
    Network network = cm.getActiveNetwork();
    if (network == null) {
        return false;
    }
    return true;
}

//将流转成字符串
public static String inputStream2String(InputStream inputStream) throws IOException {

    InputStreamReader isr = new InputStreamReader(inputStream);
    char[] chars = new char[1024];
    int len = 0;
    StringBuffer stringBuffer = new StringBuffer();
    while ((len = isr.read(chars)) != -1) {
        String s = new String(chars, 0, len);
        stringBuffer.append(s);
    }
    return stringBuffer.toString();

}

}