java常用string inputStream转换

 

1、String –> InputStream

InputStrem is = new ByteArrayInputStream(str.getBytes());
或者
ByteArrayInputStream stream= new ByteArrayInputStream(str.getBytes());

 2、InputStream–>String

inputStream input;

StringBuffer out = new StringBuffer();
     byte[] b = new byte[4096];
     for (int n; (n = input.read(b)) != -1;) {
          out.append(new String(b, 0, n));
     }
out.toString();

3、Reader –>String

BufferedReader in = new BufferedReader(new InputStreamReader(is));
StringBuffer buffer = new StringBuffer();
String line = " ";
while ((line = in.readLine()) != null){
     buffer.append(line);
}
return buffer.toString();

4、String–>Reader

Reader reader = null;
BufferedReader r = new BufferedReader(reader);
StringBuilder b = new StringBuilder();
String line;
while((line=r.readLine())!=null) {
     b.append(line);
     b.append(“\r\n”);
}
b.toString();

 

分类: Java SE

 

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Java中InputStream和String之间的转换方法

 在Java中InputStream和String之间的转化十分普遍，本文主要是总结一下转换的各种方法，包括JDK原生提供的，还有一些外部依赖提供的。

1、InputStream转化为String
1.1 JDK原生提供
方法一：
byte[] bytes = new byte[0];
bytes = new byte[inputStream.available()];
inputStream.read(bytes);
String str = new String(bytes);
 
方法二：
String result = new BufferedReader(new InputStreamReader(inputStream))
.lines().collect(Collectors.joining(System.lineSeparator()));
 
方法三：
String result = new BufferedReader(new InputStreamReader(inputStream))
.lines().parallel().collect(Collectors.joining(System.lineSeparator()));
 
方法四：
Scanner s = new Scanner(inputStream).useDelimiter("\\A");
String str = s.hasNext() ? s.next() : "";
 
方法五：
String resource = new Scanner(inputStream).useDelimiter("\\Z").next();
return resource;
 
方法六：
StringBuilder sb = new StringBuilder();
String line;

BufferedReader br = new BufferedReader(new InputStreamReader(inputStream));
while ((line = br.readLine()) != null) {
sb.append(line);
}
String str = sb.toString();
return str;
 
方法七：
ByteArrayOutputStream result = new ByteArrayOutputStream();
byte[] buffer = new byte[1024];
int length;
while ((length = inputStream.read(buffer)) != -1) {
result.write(buffer, 0, length);
}
String str = result.toString(StandardCharsets.UTF_8.name());
return str;
 

方法八：
BufferedInputStream bis = new BufferedInputStream(inputStream);
ByteArrayOutputStream buf = new ByteArrayOutputStream();
int result = bis.read();
while(result != -1) {
buf.write((byte) result);
result = bis.read();
}
String str = buf.toString();
return str;
 
1.2 Apache Common提供
方法九：
StringWriter writer = new StringWriter();
IOUtils.copy(inputStream, writer, StandardCharsets.UTF_8.name());
String str = writer.toString();
 
方法十：
String str = IOUtils.toString(inputStream, "utf-8");
 
1.3 Google Guava提供
方法十一：
String str = CharStreams.toString(new InputStreamReader(inputStream, StandardCharsets.UTF_8));
 
方法十二：
String str = new String(ByteStreams.toByteArray(inputStream));
 
针对一个2MB的文件的输入流，多次执行测试如下(单位是毫秒)：

方法十: 111
方法十一: 236
方法十二: 36
方法一: 36
方法二: 87
方法三: 66
方法四: 101
方法五: 178
方法六: 40
方法七: 21
方法八: 107
方法九: 31

从上述结果来看，方法七和方法九更好一些，而方法五和方法十一会更差一些。

2、String转化为InputStream
2.1 JDK原生提供
InputStream is = new ByteArrayInputStream(str.getBytes());

2.2 Apache Common提供
InputStream targetStream = IOUtils.toInputStream(str, StandardCharsets.UTF_8.name());

2.3 Google Guava提供
InputStream targetStream =
new ReaderInputStream(CharSource.wrap(str).openStream(), StandardCharsets.UTF_8.name());
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原文链接：https://blog.csdn.net/lmy86263/article/details/60479350