Java 将json标记(字节[])作为流读取
假设我有一些json响应,比如:Java 将json标记(字节[])作为流读取,java,json,jackson,Java,Json,Jackson,假设我有一些json响应,比如: { byteProp: [1, 3, 2, ... some very large byte content] } 我想以流的形式获取byteProp。我从一开始就认为应该创建如下解析器: JsonFactory jfactory = new JsonFactory(); JsonParser jParser = jfactory.createJsonParser( myJsonStream); 但问题是,我不认为有机会将我的byteProp获取
{
byteProp: [1, 3, 2, ... some very large byte content]
}
我想以流的形式获取byteProp
。我从一开始就认为应该创建如下解析器:
JsonFactory jfactory = new JsonFactory();
JsonParser jParser = jfactory.createJsonParser( myJsonStream);
但问题是,我不认为有机会将我的byteProp
获取为流,获取此属性的唯一方法是使用类似的东西(假设我们使用了正确的标记)
它仍然会将所有byteProp
内容提取到内存中,这是我希望避免的情况
有没有办法将单个json属性读取为流?类似的方法应该可以工作,可以根据需要进行改进:
ByteArrayOutputStream os = new ByteArrayOutputStream();
JsonFactory jfactory = new JsonFactory();
JsonParser jParser = jfactory.createJsonParser(new FileInputStream(new File("data/json.json")));
if (jParser.nextToken() != JsonToken.START_OBJECT) {
return;
}
while (jParser.nextToken() != JsonToken.END_OBJECT) {
String fieldName = jParser.getCurrentName();
jParser.nextToken();
if (fieldName.equals("byteProp")) {
byte[] bytes = new byte[1024];
int read = 0;
while (jParser.nextToken() != JsonToken.END_ARRAY) {
if (read >= bytes.length) {
os.write(bytes, 0, read);
os.flush();
bytes = new byte[1024];
read = 0;
}
bytes[read++] = jParser.getByteValue();
}
if (read >= 0) {
os.write(bytes, 0, read);
os.flush();
}
}
}
System.out.println(new String(os.toByteArray()));
根据您的需要,将替换为tearrayoutputstream
,类似于文件输出流
ByteArrayOutputStream os = new ByteArrayOutputStream();
JsonFactory jfactory = new JsonFactory();
JsonParser jParser = jfactory.createJsonParser(new FileInputStream(new File("data/json.json")));
if (jParser.nextToken() != JsonToken.START_OBJECT) {
return;
}
while (jParser.nextToken() != JsonToken.END_OBJECT) {
String fieldName = jParser.getCurrentName();
jParser.nextToken();
if (fieldName.equals("byteProp")) {
byte[] bytes = new byte[1024];
int read = 0;
while (jParser.nextToken() != JsonToken.END_ARRAY) {
if (read >= bytes.length) {
os.write(bytes, 0, read);
os.flush();
bytes = new byte[1024];
read = 0;
}
bytes[read++] = jParser.getByteValue();
}
if (read >= 0) {
os.write(bytes, 0, read);
os.flush();
}
}
}
System.out.println(new String(os.toByteArray()));