说明：文件I/O的关键类比较多，这里总结一下。
参考：《Java 7 入门经典》
1、Java输入流
图1，java常用输入输出流的结构图（第一版）
1）标准流
|
标准流 |
类型 |
方法 |
|
System.in |
InputStream |
|
|
System.out |
PrintStream |
例如：printf(“b=%2$-15.2f”,a,b) |
|
System.err |
2）字节型
典型方式-1：从文件中读取
File file = ...
InputStream in = null;
try {
in = new BufferedInputStream(new FileInputStream(file));
...
finally {
if (in != null) {
in.close();
}
}
}
典型方式-2：从文件中读取（java1.7）
Files.newInputStream(Path file)
Path file = Path.get(“D:/cao.java”)
InputStream in = null;
try {
in = new BufferedIntputStream(Files.newInputStream(file));
...
finally {
if (out != null) {
out.close();
}
}
}
典型方式-3从控制台读取
in = new BufferedInputStream(System.in);
3）字符型
典型方式-1：从文件中读取（***不太好***）
BufferedReader buf=new BufferedReader(new FileReader(String file))//不能编码
BufferedReader buf = new BufferedReader(new FileReader("file.java"));
典型方式-2：从文件中读取（***较好***）
BufferedReader buf=new BufferedReader(new InputStreamReader(new FileInputStream(String file), String charsetName)) //可以编码 InputStreamReader(InputStream in, String charsetName) File file = ... ... BufferedReader buf = new BufferedReader(new InputStreamReader(new FileInputStream(String file), “utf-8”);
典型方式-3：从文件中读取（***java1.7最佳**）
InputStream newInputStream(Path path,OpenOption... options) Path file=Paths.get(); … BufferedInputStream in=new BufferedInputStream(Files.newInputStream(file, Charset.forName(“UTF-8”)))
4)通道输入流
(-- 待完成 --)
2、Java输出流
1）字节型
典型方式-1：打开文件的输出流
FileOutputStream (File file,boolean append),append为true追加模式，没有则新建
File file = ...
OutputStream out = null;
try {
out = new BufferedOutputStream(new FileOutputStream(file));
...
finally {
if (out != null) {
out.close();
}
}
}
典型方式-2：打开文件的输出流（java1.7）
Files.newOutputStream(Pathfile,CREATE,APPEND),没有则新建，追加模式
Path file = Path.get(“D:/caoyanfeng.java”)
OutputStream out = null;
try {
out = new BufferedOutputStream(Files.newOutputStream(file));
...
finally {
if (out != null) {
out.close();
}
}
}
2）字符型
典型方式-1：打开文件的输出流(***不好的方式***)
FileWriter(File file,boolean
append),append为true追加模式，没有则新建。不能指定编码方式。
File file = ...
Writer writer = null;
try {
writer = new BufferedWriter(new FileWriter(file));
...
finally {
if (writer != null) {
writer.close();
}
}
}
典型方式-2：打开文件的输出流（***较好方式***）
OutputStreamWriter(new
FileOutputStream(File file, booleanappend),"UTF-8")
, append为true追加模式，没有则新建,utf-8编码
File file = ... Writer writer = null; try { writer = new OutputStreamWriter(new FileOutputStream(file),”UTF-8”); ... writer.write("曹艳丰"); writer.flush; finally { if (writer != null) { writer.close(); } } }典型方式-3：打开文件的输出流（***最佳方式***）
Files.newBufferedWriter(Path file,Charset.forName(“UTF-8”), CREATE,APPEND),没有则新建，追加模式,utf-8编码
Path file = Path.get(“D:/cao.java”) Writer writer = null; try { writer = new BufferedWriter(Files. newBufferedWriter (Path file,Charset.forName(“UTF-8”), CREATE,APPEND)); ... finally { if (writer != null) { writer.close(); } } }3）通道输出流
(-- 待完成 --)
3、Android输入流
Android 的输入输出流基本和java相同，只是路径需要使用手机路径。另外，context提供了操作程序路径下的两个字节流。
FileInputStream openFileInput (String name)
FileOutputStream openFileOutput (String name,int mode)
1）字节型
获得文件的FileInputStream，然后进行封装
BufferedInputStream in = new BufferedInputStream(new FileInputStream(File file));
典型例子-1：操作本程序data文件夹的IO
Android的context方法
FileInputStream openFileInput (String name)典型例子-2：指定路径下的IO(同java)
File file=new File(dir,"/data/com.iteye.androidtoast/androidtoast.txt"); BufferedInputStream in = new BufferedInputStream(new FileInputStream(File file));2）字符型
3、 Android输出流
1）字节型
获得文件的FileOutputStream，然后进行封装
再将FileOutputStreamfos进行封装进PrintStream 或BufferedOutputStream
BufferedOutputStream out=new BufferedOutputStream(openFileInput (String name)或
PrintStream out=new BufferedOutputStream(openFileInput (String name))
典型例子-1：操作本程序data文件夹的IO
FileOutputStream openFileOutput (String name, int mode) 即 FileOutputStream fos= openFileInput (String name)
典型例子-2：操作指定文件夹的下的IO
FileOutputStream(File file, boolean append)，与java字节流相同 File dir = Environment.getDataDirectory();//得到data目录 File file=new File(dir,"/data/com.iteye.androidtoast/androidtoast.txt"); FileOutputStream out=new FileOutputStream(file, true);
2）字符型
典型例子-1：打开文件的输出流(***同java，不好的方式***)
File dir = Environment.getDataDirectory();//得到data目录 File file=new File(dir,"/data/com.iteye.androidtoast/androidtoast.txt"); FileWriter fw=new FileWriter(file,true);
到这里可以直接写入文件，也可以进行再次封装
BufferedWriter bw=new BufferedWriter(new FileWriter(file,true));
典型方式-2：打开文件的输出流（***同java，较好方式***）
File file=new File(dir,"/data/com.iteye.androidtoast/androidtoast.txt"); OutputStreamWriter(new FileOutputStream(File file, boolean append),"UTF-8") // append为true追加模式，没有则新建,utf-8编码