import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.Reader;
import java.io.StringWriter;
import java.io.Writer;

public class FileUtils {
    
    
    
    /**
     * 功能：向指定的文件中写入字符串（指定是否覆盖）
     * @param outputFile 要写入的文件
     * @param sb         要写入的字符串
     * @param encoding   字符编码
     * @param append     是否要追加或者覆盖原有内容
     * */
    
    public static void writeFile(File outputFile, String sb, String encoding, boolean append)
      {
        BufferedWriter fw = null;
        try {
          if (!(outputFile.exists()))
            outputFile.createNewFile();

          OutputStreamWriter osw = null;
          if (null != encoding) {
            osw = new OutputStreamWriter(new FileOutputStream(outputFile, append), encoding);
          }
          else
            osw = new OutputStreamWriter(new FileOutputStream(outputFile, append));
          fw = new BufferedWriter(osw);
          fw.write(sb);      
        }
        catch (IOException ex) {
           ex.printStackTrace();
        }
        finally {
          try {
            if (fw != null)
              fw.close();
           }
          catch (IOException e)
          {
            e.printStackTrace();
          }
        }
      }
  
    /**
     * 功能：得到文件的内容
     * @param   is         读入流(InputStream)
     * @return  String    返回的字符串    
     * 
     * */    
    public static String streamToString(InputStream is) throws IOException {
        if (is != null) {
          Writer writer = new StringWriter();

          char[] buffer = new char[1024];
          try {
            Reader reader = new BufferedReader(new InputStreamReader(is, "UTF-8"));
            int n;
            while ((n = reader.read(buffer)) != -1) {              
              writer.write(buffer, 0, n);
            }
          } finally {
            is.close();
          }
          return writer.toString();
        }
        return "";
      }
    /**
     * 功能：向指定的文件中写入字符串（指定是否覆盖）
     * @param f               要写入的文件
     * @param string          要写入的字符串
     * @throws IOException 
     * */
    public static  void writeFile(String string,File f) throws IOException {
            FileWriter writer=new FileWriter(f);
            BufferedWriter bw = new BufferedWriter(writer);
            bw.write(string);
            bw.close();
            writer.close();
         }

    /**
     * 功能：读文件
     * @param InputStream     要写入的文件
     * @return string         返回的字符串
     * @throws IOException 
     * */
    public static String readFile(InputStream in) throws Exception{
        StringBuilder builder=new StringBuilder();
        BufferedReader br = new BufferedReader(new InputStreamReader(in));
        String line=br.readLine();
        while (line != null) {
              builder.append(line + "\n");
              line = br.readLine();
          }
        return builder.toString();        
    }    
}