InputStream转换为String的11种方式
我发现了11种主要方法(请参见下文)。我写了一些性能测试(请参见下面的结果):将InputStream转换为字符串的方法:使用IOUtils.toString(Apache Utils)String result = IOUtils.toString(inputStream, StandardCharsets.UTF_8);使用CharStreams(Guava)String result = C
我发现了11种主要方法(请参见下文)。我写了一些性能测试(请参见下面的结果):
将InputStream转换为字符串的方法:
使用IOUtils.toString(Apache Utils)
String result = IOUtils.toString(inputStream, StandardCharsets.UTF_8);
使用CharStreams(Guava)
String result = CharStreams.toString(new InputStreamReader(
inputStream, Charsets.UTF_8));
使用Scanner(JDK)
Scanner s = new Scanner(inputStream).useDelimiter("\\A");
String result = s.hasNext() ? s.next() : "";
使用流API(Java 8)。警告:此解决方案会将不同的换行符(如\r\n)转换为\n。
String result = new BufferedReader(new InputStreamReader(inputStream))
.lines().collect(Collectors.joining("\n"));
使用并行流API(Java 8)。警告:此解决方案会将不同的换行符(如\r\n)转换为\n。
String result = new BufferedReader(new InputStreamReader(inputStream)).lines()
.parallel().collect(Collectors.joining("\n"));
使用InputStreamReader和StringBuilder(JDK)
final int bufferSize = 1024;
final char[] buffer = new char[bufferSize];
final StringBuilder out = new StringBuilder();
Reader in = new InputStreamReader(stream, StandardCharsets.UTF_8);
int charsRead;
while((charsRead = in.read(buffer, 0, buffer.length)) > 0) {
out.append(buffer, 0, charsRead);
}
return out.toString();
使用StringWriter和IOUtils.copy(Apache Commons)
StringWriter writer = new StringWriter();
IOUtils.copy(inputStream, writer, "UTF-8");
return writer.toString();
使用ByteArrayOutputStream和inputStream.read(JDK)
ByteArrayOutputStream result = new ByteArrayOutputStream();
byte[] buffer = new byte[1024];
int length;
while ((length = inputStream.read(buffer)) != -1) {
result.write(buffer, 0, length);
}
// StandardCharsets.UTF_8.name() > JDK 7
return result.toString("UTF-8");
使用BufferedReader(JDK)。警告:此解决方案将不同的换行符(如\n\r)转换为line.separator系统属性(例如,在Windows中转换为“ \ r \ n”)。
String newLine = System.getProperty("line.separator");
BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
StringBuilder result = new StringBuilder();
boolean flag = false;
for (String line; (line = reader.readLine()) != null; ) {
result.append(flag? newLine: "").append(line);
flag = true;
}
return result.toString();
使用BufferedInputStream和ByteArrayOutputStream(JDK)
BufferedInputStream bis = new BufferedInputStream(inputStream);
ByteArrayOutputStream buf = new ByteArrayOutputStream();
int result = bis.read();
while(result != -1) {
buf.write((byte) result);
result = bis.read();
}
// StandardCharsets.UTF_8.name() > JDK 7
return buf.toString("UTF-8");
使用inputStream.read()和StringBuilder(JDK)。警告:此解决方案存在Unicode问题,例如俄语文本(仅适用于非Unicode文本)
int ch;
StringBuilder sb = new StringBuilder();
while((ch = inputStream.read()) != -1)
sb.append((char)ch);
reset();
return sb.toString();
警告:
解决方案4、5和9将不同的换行符转换为同一个。
解决方案11不能正确处理Unicode文本
性能测试
针对小型String(长度= 175),github中 url的性能测试(模式=平均时间,系统= Linux,满分1,343分是最好的):
Benchmark | Mode | Cnt | Score | Error | Units |
---|---|---|---|---|---|
8. ByteArrayOutputStream and read (JDK) | avgt | 10 | 1,343 | ± 0,028 | us/op |
6. InputStreamReader and StringBuilder (JDK) | avgt | 10 | 6,980 | ± 0,404 | us/op |
10. BufferedInputStream, ByteArrayOutputStream | avgt | 10 | 7,437 | ± 0,735 | us/op |
11. InputStream.read() and StringBuilder (JDK) | avgt | 10 | 8,977 | ± 0,328 | us/op |
7. StringWriter and IOUtils.copy (Apache) | avgt | 10 | 10,613 | ± 0,599 | us/op |
1. IOUtils.toString (Apache Utils) | avgt | 10 | 21,544 | ± 0,527 | us/op |
3. Scanner (JDK) | avgt | 10 | 12,083 | ± 0,293 | us/op |
2. CharStreams (guava) | avgt | 10 | 12,999 | ± 0,514 | us/op |
4. Stream Api (Java 8) | avgt | 10 | 15,811 | ± 0,605 | us/op |
9. BufferedReader (JDK) | avgt | 10 | 16,038 | ± 0,711 | us/op |
5. parallel Stream Api (Java 8) | avgt | 10 | 21,544 | ± 0,583 | us/op |
针对大型String(长度= 50100),github中的 url的性能测试(模式=平均时间,系统= Linux,得分200,715为最佳):
Benchmark | Mode | Cnt | Score | Error | Units |
---|---|---|---|---|---|
8. ByteArrayOutputStream and read (JDK) | avgt | 10 | 200,715 | ± 18,103 | us/op |
1. IOUtils.toString (Apache Utils) | avgt | 10 | 300,019 | ± 8,751 | us/op |
6. InputStreamReader and StringBuilder (JDK) | avgt | 10 | 347,616 | ± 130,348 | us/op |
7. StringWriter and IOUtils.copy (Apache) | avgt | 10 | 352,791 | ± 105,337 | us/op |
2. CharStreams (guava) | avgt | 10 | 420,137 | ± 59,877 | us/op |
9. BufferedReader (JDK) | avgt | 10 | 632,028 | ± 17,002 | us/op |
5. parallel Stream Api (Java 8) | avgt | 10 | 662,999 | ± 46,199 | us/op |
4. Stream Api (Java 8) | avgt | 10 | 701,269 | ± 82,296 | us/op |
10. BufferedInputStream, ByteArrayOutputStream | avgt | 10 | 740,837 | ± 5,613 | us/op |
3. Scanner (JDK) | avgt | 10 | 751,417 | ± 62,026 | us/op |
11. InputStream.read() and StringBuilder (JDK) | avgt | 10 | 2919,350 | ± 1101,942 | us/op |
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