如何將兩個文件合併？

在Java面試題中，我們經常會遇到將兩個文件合併的題目，這一次我特意認真做了一下這個題目，用了三種方法實現兩個文件的合併。

第一種方法：

需要使用到FileInputStream類和FileOutputStream類：

代碼如下：

File mergeFile=new File("D:\\eclipse\\merge.txt");
File file1=new File("context.txt");
File file2=new File("words.conf");
if(!mergeFile.exists()){
try {
mergeFile.createNewFile();
FileOutputStream mergeStream=new FileOutputStream(mergeFile);
FileInputStream inputStream1=new FileInputStream(file1);
FileInputStream inputStream2=new FileInputStream(file2);
byte[] b=new byte[100];
while((inputStream2.read(b))!=-1){
mergeStream.write(b);
}
while((inputStream1.read(b))!=-1){
mergeStream.write(b);
}
mergeStream.flush();
} catch (IOException e) {
e.printStackTrace();
}
}

注意：在輸出流之後，最好養成flush()的習慣；

第二種方法，需要用到SequenceInputStream和FileInputStream和FileOutputStream：

try {
FileOutputStream fileOutputStream=new FileOutputStream(new File("D:\\eclipse\\merge.txt"));
FileInputStream inputStream1=new FileInputStream("context.txt");
FileInputStream inputStream2=new FileInputStream("words.conf");
SequenceInputStream sequenceInputStream=new SequenceInputStream(inputStream2, inputStream1);
byte[] b=new byte[100];
while((sequenceInputStream.read(b))!=-1){
fileOutputStream.write(b);
}
} catch (Exception e) {
e.printStackTrace();
}

第三種方法，需要用到RandomAccessFile 

try {
RandomAccessFile writeFile=new RandomAccessFile(new File("D:\\eclipse\\merge.txt"), "rw");
RandomAccessFile readFile=new RandomAccessFile("context.txt", "r");
RandomAccessFile readFile2=new RandomAccessFile("words.conf", "r");
byte[] b=new byte[100];
while((readFile.read(b))!=-1){
writeFile.write(b);
}
while((readFile2.read(b))!=-1){
writeFile.write(b);
}
} catch (Exception e) {
e.printStackTrace();
}