int read(byte[] b, int off, int len)
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2023-12-01
描述 (Description)
java.util.zip.ZipInputStream.read(byte[] buf, int off, int len)方法从当前ZIP条目读入字节数组。 如果len不为零,则该方法将阻塞,直到某些输入可用为止; 否则,不读取任何字节,返回0。
声明 (Declaration)
以下是java.util.zip.ZipInputStream.read(byte[] buf, int off, int len)方法的声明。
public int read(byte[] buf, int off, int len)
throws IOException
参数 (Parameters)
buf - 读取数据的缓冲区。
off - 目标数组中的起始偏移量b。
len - 读取的最大字节数。
返回值 (Returns)
读取的实际字节数,如果到达流的末尾,则返回-1。
异常 (Exceptions)
NullPointerException - 如果buf为null。
IndexOutOfBoundsException - 如果off为负数,则len为负数,或者len为buf.length-off。
ZipException - 如果发生ZIP文件错误。
IOException - 如果发生I/O错误。
先决条件
在D:》 test 》目录中创建一个文件Hello.txt,其中包含以下内容。
This is an example.
例子 (Example)
以下示例显示了java.util.zip.ZipInputStream.read(byte [] buf,int off,int len)方法的用法。
package cn.xnip;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Date;
import java.util.zip.Adler32;
import java.util.zip.CheckedOutputStream;
import java.util.zip.ZipEntry;
import java.util.zip.ZipInputStream;
import java.util.zip.ZipOutputStream;
public class ZipInputStreamDemo {
private static String SOURCE_FILE = "D:\\test\\Hello.txt";
private static String TARGET_FILE = "D:\\test\\Hello.zip";
public static void main(String[] args) {
try {
createZipFile();
readZipFile();
} catch(IOException ioe) {
System.out.println("IOException : " + ioe);
}
}
private static void createZipFile() throws IOException{
FileOutputStream fout = new FileOutputStream(TARGET_FILE);
CheckedOutputStream checksum = new CheckedOutputStream(fout, new Adler32());
ZipOutputStream zout = new ZipOutputStream(checksum);
FileInputStream fin = new FileInputStream(SOURCE_FILE);
ZipEntry zipEntry = new ZipEntry(SOURCE_FILE);
zout.putNextEntry(zipEntry);
int length;
byte[] buffer = new byte[1024];
while((length = fin.read(buffer)) > 0) {
zout.write(buffer, 0, length);
}
zout.closeEntry();
fin.close();
zout.close();
}
private static void readZipFile() throws IOException{
ZipInputStream zin = new ZipInputStream(new FileInputStream(TARGET_FILE));
ZipEntry entry;
while((entry = zin.getNextEntry())!=null){
System.out.printf("File: %s Modified on %TD %n",
entry.getName(), new Date(entry.getTime()));
extractFile(entry, zin);
System.out.printf("Zip file %s extracted successfully.", SOURCE_FILE);
zin.closeEntry();
}
zin.close();
}
private static void extractFile(final ZipEntry entry, ZipInputStream is)
throws IOException {
FileOutputStream fos = null;
try {
fos = new FileOutputStream(entry.getName());
final byte[] buf = new byte[1024];
int read = 0;
int length;
while ((length = is.read(buf, 0, buf.length)) >= 0) {
fos.write(buf, 0, length);
}
} catch (IOException ioex) {
fos.close();
}
}
}
让我们编译并运行上面的程序,这将产生以下结果 -
File: D:\test\Hello.txt Modified on 05/22/17
Zip file D:\test\Hello.txt extracted successfully.