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做一个解析网站并将网站转换为字符串的小应用，如下图所示

运行结果.jpg

步骤如下：

1、UI布局

2、在MainActivity中

首先找到添加的控件

privatevoidfindViews(){        mEditText = (EditText) findViewById(R.id.editText);        mTextView = (TextView) findViewById(R.id.textView);        mButton = (Button) findViewById(R.id.button);    }

设置点击事件

privatevoidsetListeners(){        mButton.setOnClickListener(this);    }

在onClick()事件中添加EditText网址的读取

privateStringgetEditText(){returnmEditText !=null? mEditText.getText().toString() :"";    }

在onClick()事件中添加AsyncTask异步任务处理

classRequestNetworkDataTaskextendsAsyncTask{//在后台work之前@Overrideprotectedvoid onPreExecute() {super.onPreExecute();//主线程//UI Loading}@OverrideprotectedStringdoInBackground(String[] params) {//请求网络数据Stringresult = requestData(params[0]);returnresult;        }@Overrideprotectedvoid onPostExecute(Stringresult) {super.onPostExecute(result);//设置TextViewmTextView.setText(result);        }    }

请求网络数据

privateStringrequestData(String urlString){try{            URL url =newURL(urlString);            HttpURLConnection connection = (HttpURLConnection) url.openConnection();            connection.setConnectTimeout(30000);            connection.setRequestMethod("GET");            connection.connect();intresponseCode = connection.getResponseCode();            String result =null;if(responseCode == HttpURLConnection.HTTP_OK) {                InputStream inputStream = connection.getInputStream();                Reader reader =newInputStreamReader(inputStream,"UTF-8");char[] buffer =newchar[1024];                reader.read(buffer);                result =newString(buffer);            }else{            }returnresult;        }catch(IOException e) {            e.printStackTrace();        }returnnull;    }

3、在AndroidManifest中添加网络权限

完整项目代码

packagecom.geekband.networkdemo;importandroid.os.AsyncTask;importandroid.support.v7.app.AppCompatActivity;importandroid.os.Bundle;importandroid.view.View;importandroid.widget.Button;importandroid.widget.EditText;importandroid.widget.TextView;importjava.io.IOException;importjava.io.InputStream;importjava.io.InputStreamReader;importjava.io.Reader;importjava.net.HttpURLConnection;importjava.net.URL;publicclassMainActivityextendsAppCompatActivityimplementsView.OnClickListener{privateEditText mEditText;privateButton mButton;privateTextView mTextView;@OverrideprotectedvoidonCreate(Bundle savedInstanceState){super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        findViews();        setListeners();    }privatevoidsetListeners(){        mButton.setOnClickListener(this);    }privatevoidfindViews(){        mEditText = (EditText) findViewById(R.id.editText);        mButton = (Button) findViewById(R.id.button);        mTextView = (TextView) findViewById(R.id.textView);    }@OverridepublicvoidonClick(View v){switch(v.getId()) {caseR.id.button:                String url = getEditText();//申请网络权限//                String data = requestData(url);newRequestNetworkDataTask().execute(url);break;        }    }privateStringgetEditText(){returnmEditText !=null? mEditText.getText().toString() :"";    }//异步任务处理classRequestNetworkDataTaskextendsAsyncTask{//在后台work之前@OverrideprotectedvoidonPreExecute(){super.onPreExecute();//主线程//UI Loading}@OverrideprotectedStringdoInBackground(String[] params){//请求网络数据String result = requestData(params[0]);returnresult;        }@OverrideprotectedvoidonPostExecute(String result){super.onPostExecute(result);//设置TextViewmTextView.setText(result);        }    }privateStringrequestData(String urlString){try{            URL url =newURL(urlString);            HttpURLConnection connection = (HttpURLConnection) url.openConnection();            connection.setConnectTimeout(30000);            connection.setRequestMethod("GET");            connection.connect();intresponseCode = connection.getResponseCode();            String result =null;if(responseCode == HttpURLConnection.HTTP_OK) {                InputStream inputStream = connection.getInputStream();                Reader reader =newInputStreamReader(inputStream,"UTF-8");char[] buffer =newchar[1024];                reader.read(buffer);                result =newString(buffer);            }else{            }returnresult;        }catch(IOException e) {            e.printStackTrace();        }returnnull;    }}