Question

Java代码生成的Json字段和写入的顺序有关吗

Answer 1

package net.csdn.blog.chaijunkun.util;

import java.io.IOException;

import org.codehaus.jackson.JsonGenerationException;
import org.codehaus.jackson.JsonGenerator;
import org.codehaus.jackson.JsonProcessingException;
import org.codehaus.jackson.impl.JsonWriteContext;
import org.codehaus.jackson.map.JsonSerializer;
import org.codehaus.jackson.map.SerializerProvider;
import org.codehaus.jackson.util.CharTypes;

public class StringUnicodeSerializer extends JsonSerializer<String> {

private final char[] HEX_CHARS = "0123456789ABCDEF".toCharArray();
private final int[] ESCAPE_CODES = CharTypes.get7BitOutputEscapes();

private void writeUnicodeEscape(JsonGenerator gen, char c) throws IOException {
gen.writeRaw('\\');
gen.writeRaw('u');
gen.writeRaw(HEX_CHARS[(c >> 12) & 0xF]);
gen.writeRaw(HEX_CHARS[(c >> 8) & 0xF]);
gen.writeRaw(HEX_CHARS[(c >> 4) & 0xF]);
gen.writeRaw(HEX_CHARS[c & 0xF]);
}

private void writeShortEscape(JsonGenerator gen, char c) throws IOException {
gen.writeRaw('\\');
gen.writeRaw(c);
}

@Override
public void serialize(String str, JsonGenerator gen,
SerializerProvider provider) throws IOException,
JsonProcessingException {
int status = ((JsonWriteContext) gen.getOutputContext()).writeValue();
switch (status) {
case JsonWriteContext.STATUS_OK_AFTER_COLON:
gen.writeRaw(':');
break;
case JsonWriteContext.STATUS_OK_AFTER_COMMA:
gen.writeRaw(',');
break;
case JsonWriteContext.STATUS_EXPECT_NAME:
throw new JsonGenerationException("Can not write string value here");
}
gen.writeRaw('"');//写入JSON中字符串的开头引号
for (char c : str.toCharArray()) {
if (c >= 0x80){
writeUnicodeEscape(gen, c); // 为所有非ASCII字符生成转义的unicode字符
}else {
// 为ASCII字符中前128个字符使用转义的unicode字符
int code = (c < ESCAPE_CODES.length ? ESCAPE_CODES[c] : 0);
if (code == 0){
gen.writeRaw(c); // 此处不用转义
}else if (code < 0){
writeUnicodeEscape(gen, (char) (-code - 1)); // 通用转义字符
}else {
writeShortEscape(gen, (char) code); // 短转义字符 (\n \t ...)
}
}
}
gen.writeRaw('"');//写入JSON中字符串的结束引号
}

}