在Android界面上显示和获取Logcat日志输出的方法

//第一个是Logcat ，也就是我们想要获取的log日志
//第二个是 -s 也就是表示过滤的意思
//第三个就是 我们要过滤的类型 W表示warm ，我们也可以换成 D ：debug， I：info，E：error等等
String[] running = new String[]{"logcat","-s","adb logcat *: W"};

Process exec = Runtime.getRuntime().exec(running)；

final InputStream is = exec.getInputStream

  new Thread() {
        @Override
        public void run() {
          FileOutputStream os = null;
          try {
            //新建一个路径信息
            os = new FileOutputStream("/sdcard/Log/Log.txt");
            int len = 0;
            byte[] buf = new byte[1024];
            while (-1 != (len = is.read(buf))) {
              os.write(buf, 0, len);
              os.flush();
            }
          } catch (Exception e) {
            Log.d("writelog",
                "read logcat process failed. message: "
                    + e.getMessage());
          } finally {
            if (null != os) {
              try {
                os.close();
                os = null;
              } catch (IOException e) {
                // Do nothing
              }
            }
          }
        }
      }.start();
    } catch (Exception e) {
      Log.d("writelog",
          "open logcat process failed. message: " + e.getMessage());
    }
  }

private ListView listView;
  private Button btn;  
    
  listView = (ListView) findViewById(R.id.ListLog);
  btn = (Button) findViewById(R.id.BtnLog);

/** 
   * 根据行读取内容 
   * @return 
   */ 
  public List Txt() {  
    //将读出来的一行行数据使用List存储  
    String filePath = "/sdcard/Log.txt";  
 
    List newList=new ArrayList(); 
    try {  
      File file = new File(filePath);  
      int count = 0;//初始化 key值  
      if (file.isFile() && file.exists()) {//文件存在  
        InputStreamReader isr = new InputStreamReader(new FileInputStream(file));  
        BufferedReader br = new BufferedReader(isr);  
        String lineTxt = null;  
        while ((lineTxt = br.readLine()) != null) { 
          if (!"".equals(lineTxt)) {  
            String reds = lineTxt.split("\\+")[0]; //java 正则表达式  
            newList.add(count, reds); 
            count++;  
          }  
        }  
        isr.close();  
        br.close();  
      }else {  
        Log.e("tag", "can not find file");
      }  
    } catch (Exception e) {  
      e.printStackTrace();  
    }  
    return newList;  
  }  

if (file.isFile() && file.exists()) //这一行是判断是否有文件存在

 InputStreamReader isr = new InputStreamReader(new FileInputStream(file));  
        BufferedReader br = new BufferedReader(isr);  
        String lineTxt = null;  
        while ((lineTxt = br.readLine()) != null) { 
          if (!"".equals(lineTxt)) {  
            String reds = lineTxt.split("\\+")[0]; //java 正则表达式  
            newList.add(count, reds); 
            count++;  
          }  
        }  

 ArrayAdapter adapter = new ArrayAdapter(this, R.layout.log_list_item,Txt());
 listView.setAdapter(adapter);

 /**
   * 删除Log文件
   * @param fileName 文件路径和名称
   */
  public static void delFile(String fileName){ 
    File file = new File(fileName); 
    if(file.isFile()){ 
      file.delete(); 
    } 
    file.exists(); 
  }