java 文本压缩_java对文本字符串的压缩与解压

该博客介绍了如何在Java中使用Gzip进行文本压缩和解压,以及如何结合Base64编码来处理可能出现的特殊字符问题,确保在XML传输中的兼容性。提供了一个GzipUtil类的实现,展示了压缩和解压缩字符串的方法。

public class GzipUtil {

/**

* @param str

* @return 压缩

*/

public static String compress(String str) {

if (str == null || str.length() == 0) {

return str;

}

ByteArrayOutputStream out = null;

GZIPOutputStream gzip = null;

String compress = "";

try {

out = new ByteArrayOutputStream();

gzip = new GZIPOutputStream(out);

gzip.write(str.getBytes());

gzip.close();

compress = out.toString("ISO-8859-1");

} catch (IOException e) {

e.printStackTrace();

} finally {

if (null != out) {

try {

out.close();

} catch (IOException e) {

e.printStackTrace();

}

}

}

return compress;

}

/**

* @param str

* @return 解压缩

*/

public static String uncompress(String str) {

if (str == null || str.length() == 0) {

return str;

}

ByteArrayOutputStream out = null;

ByteArrayInputStream in = null;

GZIPInputStream gzip = null;

String uncompress = "";

try {

out = new ByteArrayOutputStream();

in = new ByteArrayInputStream(str.getBytes("ISO-8859-1"));

gzip = new GZIPInputStream(in);

byte[] buffer = new byte[1024];

int offset = -1;

while ((offset = gzip.read(buffer)) != -1) {

out.write(buffer, 0, offset);

}

uncompress = out.toString();

} catch (IOException e) {

e.printStackTrace();

} finally {

if (null != gzip) {

try {

gzip.close();

} catch (IOException e) {

e.printStackTrace();

}

}

if (null != in) {

try {

in.close();

} catch (IOException e) {

e.printStackTrace();

}

}

if (null != out) {

try {

out.close();

} catch (IOException e) {

e.printStackTrace();

}

}

}

return uncompress;

}

public static void main(String[] args) throws IOException {

StringBuilder sb = new StringBuilder();

for (int i = 0; i < 10; i++) {

sb.append("代码笔记:www.note52.com");

}

String str = sb.toString();

System.out.println("原长度:" + str.length());

System.out.println("压缩后长度:" + GzipUtil.compress(str).length());

String compress = GzipUtil.compress(str);

System.out.println("压缩后内容:" + compress);

System.out.println("解压后内容:" + GzipUtil.uncompress(compress));

}

}

这段代码的压缩效率还是比较高的,对于大段文本,能压缩到原文本的10%左右。但是有个问题时,这个压缩会出现特殊字符,如果用web service调用或者其他封装成xml格式数据时候,会报异常。那么,我们可以,将压缩后的文本通过base64进行编码,解压缩之前先进行base64解码,这样就可以避免特殊字符问题了。如下面代码

public class GzipUtil {

/**

* @param str

* @return 压缩

*/

public static String compress(String str) {

if (str == null || str.length() == 0) {

return str;

}

ByteArrayOutputStream out = null;

GZIPOutputStream gzip = null;

String compress = "";

try {

out = new ByteArrayOutputStream();

gzip = new GZIPOutputStream(out);

gzip.write(str.getBytes());

gzip.close();

// 这里增加base64编码

byte[] compressed = out.toByteArray();

compress = new sun.misc.BASE64Encoder().encodeBuffer(compressed);

} catch (IOException e) {

e.printStackTrace();

} finally {

if (null != out) {

try {

out.close();

} catch (IOException e) {

e.printStackTrace();

}

}

}

return compress;

}

/**

* @param str

* @return 解压缩

*/

public static String uncompress(String str) {

if (str == null || str.length() == 0) {

return str;

}

ByteArrayOutputStream out = null;

ByteArrayInputStream in = null;

GZIPInputStream gzip = null;

String uncompress = "";

try {

out = new ByteArrayOutputStream();

// 这里增加base64解码

byte[] compressed = new sun.misc.BASE64Decoder().decodeBuffer(str);

in = new ByteArrayInputStream(compressed);

gzip = new GZIPInputStream(in);

byte[] buffer = new byte[1024];

int offset = -1;

while ((offset = gzip.read(buffer)) != -1) {

out.write(buffer, 0, offset);

}

uncompress = out.toString();

} catch (IOException e) {

e.printStackTrace();

} finally {

if (null != gzip) {

try {

gzip.close();

} catch (IOException e) {

e.printStackTrace();

}

}

if (null != in) {

try {

in.close();

} catch (IOException e) {

e.printStackTrace();

}

}

if (null != out) {

try {

out.close();

} catch (IOException e) {

e.printStackTrace();

}

}

}

return uncompress;

}

public static void main(String[] args) throws IOException {

StringBuilder sb = new StringBuilder();

for (int i = 0; i < 10; i++) {

sb.append("代码笔记:www.note52.com");

}

String str = sb.toString();

System.out.println("原长度:" + str.length());

System.out.println("压缩后长度:" + GzipUtil.compress(str).length());

String compress = GzipUtil.compress(str);

System.out.println("压缩后内容:" + compress);

System.out.println("解压后内容:" + GzipUtil.uncompress(compress));

}

}

base64编码后,就不会出现特殊字符了,完美解决xml传输问题。

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