package com.gaozewen.htmlviewer.utils;

import java.io.ByteArrayOutputStream;
import java.io.InputStream;
/**
 * 流的工具類
 * @author gzw
 * @version $Rev$
 * @des ${TODO}
 * @updateAuthor $Author$
 * @updateDes ${TODO}
 */
public class StreamUtils {
    /**
     * 讀取流的資料 返回一個字串
     * @param is 獲取流
     * @return 字串，如果解析失敗返回空
     */
    public static String readStream(InputStream is) {
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        byte[] buffer = new byte[1024];
        int len = 0;
        try {
            while((len = is.read(buffer))!= -1){
                baos.write(buffer,0,len);
            }
            is.close();
            String result = baos.toString();
            if(result.contains("gb2312")){
                return baos.toString("gb2312");
            }else if (result.contains("gbk")){
                return baos.toString("gbk");
            }
            return result;
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }
}
 

package com.gaozewen.htmlviewer;

import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.support.v7.app.AppCompatActivity;
import android.text.TextUtils;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

import com.gaozewen.htmlviewer.utils.StreamUtils;

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

public class MainActivity extends AppCompatActivity {

    private static final int LOAD_SUCCESS = 1;
    private static final int LOAD_ERROR = 2;
    private EditText mEt_url;
    private TextView mTv_result;
    private Handler mHandler = new Handler(){
        @Override
        public void handleMessage(Message msg) {
            switch (msg.what){
                case LOAD_SUCCESS:
                    String text = (String) msg.obj;
                    mTv_result.setText(text);
                    break;
                case LOAD_ERROR:
                    Toast.makeText(MainActivity.this,"載入失敗", Toast.LENGTH_SHORT).show();
                    break;
            }
        }
    };

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

        mEt_url = (EditText) findViewById(R.id.et_url);
        mTv_result = (TextView) findViewById(R.id.tv_result);
    }

    /**
     * 1. 宣告許可權
     * 2. 開啟子執行緒
     *
     * @param view
     */
    public void viewHtmlSource(View view) {
        final String str_url = mEt_url.getText().toString().trim();
        if (TextUtils.isEmpty(str_url)) {
            Toast.makeText(this, "url不能為空", Toast.LENGTH_SHORT).show();
            return;
        }
        new Thread() {
            @Override
            public void run() {
                try {
                    URL url = new URL(str_url);
                    HttpURLConnection conn = (HttpURLConnection) url.openConnection();
                    conn.setRequestMethod("GET");
                    int code = conn.getResponseCode();
                    if (code == 200){
                        InputStream is = conn.getInputStream();
                        // 將輸入流轉化為字串
                        String text = StreamUtils.readStream(is);

                        Message msg = Message.obtain();
                        msg.obj = text;
                        msg.what = LOAD_SUCCESS;
                        mHandler.sendMessage(msg);
                    }else {
                        Message msg = Message.obtain();
                        msg.what = LOAD_ERROR;
                        mHandler.sendMessage(msg);
                    }
                } catch (Exception e) {
                    e.printStackTrace();
                    Message msg = Message.obtain();
                    msg.what = LOAD_ERROR;
                    mHandler.sendMessage(msg);
                }
            }
        }.start();

    }
}