黑马程序员学习笔记 IO流详解
2015-07-03 17:02
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IO分两种流
字节流 InputStream OutputStream
字符流 Reader Writer
他们都是抽象类
具体实现
字节流 FileInputStream FileOutputStream
字符流 FileReader FileWriter
字节流转换成字符流可以用 InputSteamReader OutputStreamWriter
转换成BufferdReader BufferedWriter 他们具有缓冲区
例如:读取文件 从字节流输入到字符流输入
定义一个字节流:
Java代码
1. FileInputStream fileInputStream = new FileInputStream("d:/text.txt"); // 定义一个指向D:/TEXT.TXT 的字节流
2.
3. InputStreamReader inputStreamReader = new InputStreamReader(fileInputStream);
4. //字节流转换成InputStreamReader
5.
6. BufferedReader bufferedReader = new BufferedReader(inputSteamReader);
7. //InputStreamReader 转换成带缓存的bufferedReader
FileInputStream fileInputStream = new FileInputStream("d:/text.txt"); // 定义一个指向D:/TEXT.TXT 的字节流
InputStreamReader inputStreamReader = new InputStreamReader(fileInputStream);
//字节流转换成InputStreamReader
BufferedReader bufferedReader = new BufferedReader(inputSteamReader);
//InputStreamReader 转换成带缓存的bufferedReader
可以把读出来的内容赋值给字符
Java代码
1.
2. String ss = new String();
3. String s;
4. while((s = bufferedReader.readLine())!=null){
5. ss += s;
6. }
String ss = new String();
String s;
while((s = bufferedReader.readLine())!=null){
ss += s;
}
例如:写入文件 从字节流输出到字符流输出
Java代码
1.
2. FileOutputStream fileOutputStream = new FileOutputStream("d:/text.txt"); //定义一个
3.
4. 指向D:/TEXT.TXT文件
5.
6. OutputStreamWriter outputStreamWriter = new OutputStreamWriter(fileOutputStream);
7.
8. BufferedWriter bufferedWriter = new BufferedWriter(outputStreamWriter);
9.
10. bufferedWriter.write(s);
11.
12. bufferedWriter.close();
13. outputStreamWriter.close();
14. fileOutputStream.close();
范例代码如下:
package com.ljj.moshi.factory3;
import java.util.*;
import java.io.*;
interface Fruit{
public void grow();
public void eat();
}
class Apple implements Fruit{
public void grow(){
System.out.println("苹果在生长...");
}
public void eat(){
System.out.println("吃苹果...");
}
}
class Orange implements Fruit{
public void grow(){
System.out.println("橘子在生长...");
}
public void eat(){
System.out.println("吃橘子...");
}
}
class Banana implements Fruit{
public void grow(){
System.out.println("香蕉在生长...");
}
public void eat(){
System.out.println("吃香蕉...");
}
}
class Factory{
public static Fruit getFruit(String className){
Fruit f = null;
try{
f = (Fruit)Class.forName(className).newInstance();
}catch (Exception e){}
return f;
}
}
class PropertyOperate{
private Properties pro = null;
public PropertyOperate(){
this.pro = new Properties();
this.load();
}
//设置一个返回方法
public Properties getPro(){
return this.pro;
}
//从文件中读出属性,如果文件不存在,则创建一个默认的
private void save(){
pro.setProperty("a","Apple");
pro.setProperty("o","Orange");
//保存在文件之中
try{
pro.storeToXML(new FileOutputStream(new File("f:\\fruit.xml")),"FRUIT FACTORY TEST LJJ");
}catch (Exception e){}
}
private void load(){
File f = new File("f:\\fruit.xml");
if(f.exists()){
//文件存在则可以读取
try{
pro.loadFromXML(new FileInputStream(f));
}catch (Exception e){}
}else{
//进行创建
this.save();
}
}
}
class InputData{
private BufferedReader buf = null;
public InputData(){
this.buf = new BufferedReader(new InputStreamReader(System.in));
}
public String getString(){
String str =null;
try{
str = this.buf.readLine();
}catch(Exception e){}
return str;
}
}
public class Demo09{
public static void main(String args[]){
Properties p = new PropertyOperate().getPro();
System.out.println(p);
System.out.print("请选择所需要的类型:");
String str = new InputData().getString();
//进一步扩展,现在可以由用户自己输入要使用的类型
Fruit f = Factory.getFruit(p.getProperty(str));
f.grow();
}
}
----------
IO分两种流
字节流 InputStream OutputStream
字符流 Reader Writer
他们都是抽象类
具体实现
字节流 FileInputStream FileOutputStream
字符流 FileReader FileWriter
字节流转换成字符流可以用 InputSteamReader OutputStreamWriter
转换成BufferdReader BufferedWriter 他们具有缓冲区
例如:读取文件 从字节流输入到字符流输入
定义一个字节流:
Java代码
1. FileInputStream fileInputStream = new FileInputStream("d:/text.txt"); // 定义一个指向D:/TEXT.TXT 的字节流
2.
3. InputStreamReader inputStreamReader = new InputStreamReader(fileInputStream);
4. //字节流转换成InputStreamReader
5.
6. BufferedReader bufferedReader = new BufferedReader(inputSteamReader);
7. //InputStreamReader 转换成带缓存的bufferedReader
FileInputStream fileInputStream = new FileInputStream("d:/text.txt"); // 定义一个指向D:/TEXT.TXT 的字节流
InputStreamReader inputStreamReader = new InputStreamReader(fileInputStream);
//字节流转换成InputStreamReader
BufferedReader bufferedReader = new BufferedReader(inputSteamReader);
//InputStreamReader 转换成带缓存的bufferedReader
可以把读出来的内容赋值给字符
Java代码
1.
2. String ss = new String();
3. String s;
4. while((s = bufferedReader.readLine())!=null){
5. ss += s;
6. }
String ss = new String();
String s;
while((s = bufferedReader.readLine())!=null){
ss += s;
}
例如:写入文件 从字节流输出到字符流输出
Java代码
1.
2. FileOutputStream fileOutputStream = new FileOutputStream("d:/text.txt"); //定义一个
3.
4. 指向D:/TEXT.TXT文件
5.
6. OutputStreamWriter outputStreamWriter = new OutputStreamWriter(fileOutputStream);
7.
8. BufferedWriter bufferedWriter = new BufferedWriter(outputStreamWriter);
9.
10. bufferedWriter.write(s);
11.
12. bufferedWriter.close();
13. outputStreamWriter.close();
14. fileOutputStream.close();
范例代码如下:
package com.ljj.moshi.factory3;
import java.util.*;
import java.io.*;
interface Fruit{
public void grow();
public void eat();
}
class Apple implements Fruit{
public void grow(){
System.out.println("苹果在生长...");
}
public void eat(){
System.out.println("吃苹果...");
}
}
class Orange implements Fruit{
public void grow(){
System.out.println("橘子在生长...");
}
public void eat(){
System.out.println("吃橘子...");
}
}
class Banana implements Fruit{
public void grow(){
System.out.println("香蕉在生长...");
}
public void eat(){
System.out.println("吃香蕉...");
}
}
class Factory{
public static Fruit getFruit(String className){
Fruit f = null;
try{
f = (Fruit)Class.forName(className).newInstance();
}catch (Exception e){}
return f;
}
}
class PropertyOperate{
private Properties pro = null;
public PropertyOperate(){
this.pro = new Properties();
this.load();
}
//设置一个返回方法
public Properties getPro(){
return this.pro;
}
//从文件中读出属性,如果文件不存在,则创建一个默认的
private void save(){
pro.setProperty("a","Apple");
pro.setProperty("o","Orange");
//保存在文件之中
try{
pro.storeToXML(new FileOutputStream(new File("f:\\fruit.xml")),"FRUIT FACTORY TEST LJJ");
}catch (Exception e){}
}
private void load(){
File f = new File("f:\\fruit.xml");
if(f.exists()){
//文件存在则可以读取
try{
pro.loadFromXML(new FileInputStream(f));
}catch (Exception e){}
}else{
//进行创建
this.save();
}
}
}
class InputData{
private BufferedReader buf = null;
public InputData(){
this.buf = new BufferedReader(new InputStreamReader(System.in));
}
public String getString(){
String str =null;
try{
str = this.buf.readLine();
}catch(Exception e){}
return str;
}
}
public class Demo09{
public static void main(String args[]){
Properties p = new PropertyOperate().getPro();
System.out.println(p);
System.out.print("请选择所需要的类型:");
String str = new InputData().getString();
//进一步扩展,现在可以由用户自己输入要使用的类型
Fruit f = Factory.getFruit(p.getProperty(str));
f.grow();
}
}
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