如果您有java.io.InputStream对象,应该如何处理该对象并生成String?
假设我有一个包含文本数据的InputStream,我想将其转换为String,例如,我可以将其写入日志文件。
获取InputStream并将其转换为字符串的最简单方法是什么?
public String convertStreamToString(InputStream is) {
// ???
}
如果您有java.io.InputStream对象,应该如何处理该对象并生成String?
假设我有一个包含文本数据的InputStream,我想将其转换为String,例如,我可以将其写入日志文件。
获取InputStream并将其转换为字符串的最简单方法是什么?
public String convertStreamToString(InputStream is) {
// ???
}
当前回答
这里或多或少有sampath的答案,清理了一点并表示为函数:
String streamToString(InputStream in) throws IOException {
StringBuilder out = new StringBuilder();
BufferedReader br = new BufferedReader(new InputStreamReader(in));
for(String line = br.readLine(); line != null; line = br.readLine())
out.append(line);
br.close();
return out.toString();
}
其他回答
注意:这可能不是个好主意。此方法使用递归,因此将非常快地命中StackOverflowError:
public String read (InputStream is) {
byte next = is.read();
return next == -1 ? "" : next + read(is); // Recursive part: reads next byte recursively
}
JDK中最简单的方法是使用以下代码片段。
String convertToString(InputStream in){
String resource = new Scanner(in).useDelimiter("\\Z").next();
return resource;
}
如果使用流读取器,请确保在结束时关闭流
private String readStream(InputStream iStream) throws IOException {
//build a Stream Reader, it can read char by char
InputStreamReader iStreamReader = new InputStreamReader(iStream);
//build a buffered Reader, so that i can read whole line at once
BufferedReader bReader = new BufferedReader(iStreamReader);
String line = null;
StringBuilder builder = new StringBuilder();
while((line = bReader.readLine()) != null) { //Read till end
builder.append(line);
builder.append("\n"); // append new line to preserve lines
}
bReader.close(); //close all opened stuff
iStreamReader.close();
//iStream.close(); //EDIT: Let the creator of the stream close it!
// some readers may auto close the inner stream
return builder.toString();
}
编辑:在JDK7+上,可以使用trywithresources构造。
/**
* Reads the stream into a string
* @param iStream the input stream
* @return the string read from the stream
* @throws IOException when an IO error occurs
*/
private String readStream(InputStream iStream) throws IOException {
//Buffered reader allows us to read line by line
try (BufferedReader bReader =
new BufferedReader(new InputStreamReader(iStream))){
StringBuilder builder = new StringBuilder();
String line;
while((line = bReader.readLine()) != null) { //Read till end
builder.append(line);
builder.append("\n"); // append new line to preserve lines
}
return builder.toString();
}
}
这个很好,因为:
它可以安全地处理Charset。您可以控制读取缓冲区的大小。您可以设置生成器的长度,而不必是精确的值。不受库依赖关系的影响。适用于Java 7或更高版本。
怎么做?
public static String convertStreamToString(InputStream is) throws IOException {
StringBuilder sb = new StringBuilder(2048); // Define a size if you have an idea of it.
char[] read = new char[128]; // Your buffer size.
try (InputStreamReader ir = new InputStreamReader(is, StandardCharsets.UTF_8)) {
for (int i; -1 != (i = ir.read(read)); sb.append(read, 0, i));
}
return sb.toString();
}
对于JDK 9
public static String inputStreamString(InputStream inputStream) throws IOException {
try (inputStream) {
return new String(inputStream.readAllBytes(), StandardCharsets.UTF_8);
}
}
public String read(InputStream in) throws IOException {
try (BufferedReader buffer = new BufferedReader(new InputStreamReader(in))) {
return buffer.lines().collect(Collectors.joining("\n"));
}
}