package com.example.filedemo;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.PrintStream;

import android.os.Bundle;
import android.app.Activity;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

/**
 * 
 * @author CSUMax
 * @version 1.0 2014-4-24
 */
public class MainActivity extends Activity {

	private Button bt_main_in; // 写入文件按钮
	private Button bt_main_out; // 读取文件按钮
	private EditText et_main_in;// 输入文本框
	private TextView tv_main_out;// 显示文件内容

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

		bt_main_in = (Button) this.findViewById(R.id.bt_main_in);
		bt_main_out = (Button) this.findViewById(R.id.bt_main_out);
		et_main_in = (EditText) this.findViewById(R.id.et_main_in);
		tv_main_out = (TextView) this.findViewById(R.id.tv_main_out);

		// 点击按钮将输入框中的内容写到文件中
		bt_main_in.setOnClickListener(new OnClickListener() {

			@Override
			public void onClick(View v) {
				String fileName = "demo.txt";
				String text = et_main_in.getText().toString();
				writeToFile(text, fileName);
				et_main_in.setText("");
			}
		});

		// 点击按钮将文件中内容读取出来显示在文本框中
		bt_main_out.setOnClickListener(new OnClickListener() {

			@Override
			public void onClick(View v) {
				String fileName = "demo.txt";
				tv_main_out.setText(readFromFile(fileName));
			}
		});

	}

	/**
	 * 读取文件
	 * 
	 * @param fileName
	 * @return
	 */
	public String readFromFile(String fileName) {

		try {
			FileInputStream fis = openFileInput(fileName);
			byte[] bytes = new byte[1024];
			StringBuffer sb = new StringBuffer();
			int i = 0;
			i = fis.read(bytes);
			if (i > 0) {
				sb.append(new String(bytes, 0, i));
			}
			return sb.toString();

		} catch (Exception e) {
			e.printStackTrace();
		}

		return null;
	}

	/**
	 * 写入文件
	 * 
	 * @param text
	 *            写入的内容
	 * @param fileName
	 *            目标文件的文件名
	 */
	public void writeToFile(String text, String fileName) {
		try {
			// MODE_APPEND模式写入，即追加模式
			FileOutputStream fos = openFileOutput(fileName, MODE_APPEND);
			PrintStream ps = new PrintStream(fos);
			ps.println(text);
			ps.close();
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

}

public class ReadFileUtil {
   
    public static String readFromSdcard(String fileName) {
        String str = "";
        try {
            FileInputStream fis = new FileInputStream(fileName);
            int length = fis.available();
            byte[] bytes = new byte[length];
            int i = 0;
            i = fis.read(bytes);
            if (i > 0) {
                // 设置编码
                str = EncodingUtils.getString(bytes, "UTF-8");
            }
            fis.close();
            return str;
        } catch (Exception e) {
            // TODO: handle exception
        }
        return null;
    }
    /**
     * --注意向SD卡中的文件写入信息时，要在AndroidManifest.xml文件中加入相应的权限--
     */
    public static void writeToSdcard(String text, String fileName){
        try {
            //构造方法的第二个参数表示追加模式
            FileOutputStream fos = new FileOutputStream(fileName, true);
            byte[] bytes = text.getBytes();
            fos.write(bytes);
            fos.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    
}