如何阻止 Java 将作为命令行参数传递的 JSON 字符串分离到 args[] 的单独子单元中

Question

I want to pass this JSON String to a Java class through command line arguments.

{"body": "We should definitely meet up, man", "startDate": "2014-05-29 11:00:00", "endDate": "2014-05-29 12:00:00", "location": "Boca Raton", "subject": "This is the subject of our meeting."}

However, at every space, the String gets split up. So args[0] is

{"body":

args[1] is

"We

etc.

I want args[0] to just be

{"body": "We should definitely meet up, man", "startDate": "2014-05-29 11:00:00", "endDate": "2014-05-29 12:00:00", "location": "Boca Raton", "subject": "This is the subject of our meeting."}

I tried using double quotes, but since there are quotes in the JSON string it didn't work.

How can I do this? Thanks so much!

Answer 1

Here is a better solution:

1. Stop passing json as a command line argument.
2. Put the json in a file.
3. Pass the name of the json file as a command line argument.
4. Read the json file in your application.

Answer 2

This isn't a Java issue: it's a shell issue. So the answer depends on what shell you're using.

If you're on a UNIX-y shell, try putting the JSON within single quotes. For instance: java my.MainClass '{ "key1": "value1" }' . That'll probably work on Windows, too ... I'm not sure.

If you have a ' in your JSON, things get complicated. If your shell is Bash, one option is to replace every ' with '\\'' .

But where is the JSON coming from? If you're actually invoking this Java program from within another program, you can skip the shell altogether. Python's subprocess.call , Ruby's IO.popen , Bash's "$@" and Java's ProcessBuilder all accept an array of command-line arguments instead of a single-string command. Alternatively, logic like Ruby's Shellwords exists for just about any programming language and quotes command-line parameters so the shell parses them into exactly the bytes you specify.

Another alternative: you can pipe the JSON to your program. Invoke it like this (on UNIX):

cat | java my.MainClass
{
  "you can just type": "this stuff",
  "and it will eventually get picked up by": "Java"
}
[Ctrl-d (UNIX) or Ctrl-z (Windows)]

And read it in Java as discussed at Read/convert an InputStream to a String -- using System.in as the InputStream .

Answer 3

You need to escape the double-quote characters and surround the entire String with normal double-quotes:

java Test "{\"body\": \"We should definitely meet up, man\", \"startDate\": \"2014-05-29 11:00:00\", \"endDate\": \"2014-05-29 12:00:00\", \"location\": \"Boca Raton\", \"subject\": \"This is the subject of our meeting.\"}"

This is a Windows example.

Answer 4

Try to encode your JSON string in base64:

{"body": "We should definitely meet up, man", "startDate": "2014-05-29 11:00:00", "endDate": "2014-05-29 12:00:00", "location": "Boca Raton", "subject": "This is the subject of our meeting."}

will be encoded to

eyJib2R5IjogIldlIHNob3VsZCBkZWZpbml0ZWx5IG1lZXQgdXAsIG1hbiIsICJzdGFydERhdGUiOiAiMjAxNC0wNS0yOSAxMTowMDowMCIsICJlbmREYXRlIjogIjIwMTQtMDUtMjkgMTI6MDA6MDAiLCAibG9jYXRpb24iOiAiQm9jYSBSYXRvbiIsICJzdWJqZWN0IjogIlRoaXMgaXMgdGhlIHN1YmplY3Qgb2Ygb3VyIG1lZXRpbmcuIn0=

This eliminated spaces and other troublesome characters.

Of course, you will need to decode it back inside your program, but this is relatively easy to do.

Answer 5

The shell is removing the double quotes. Instead, you could use single quotes in the json, eg

{'networks':{'privateIP':'10.10.1.17','publicIP':'192.168.1.144'}}

Then parse it using:

ObjectMapper om = new ObjectMapper();
om.configure(JsonParser.Feature.ALLOW_SINGLE_QUOTES, true);
Networks n = om.readValue(args[0], Networks.class);

Answer 6

#!/bin/bash

JSON='
{
    "bbb":456,
    "aaaa": "SDFDS"
}
'
JSON=$(echo $JSON | sed s/\"/\\\"/g)
echo $JSON
java -Dmyparam="$JSON" Abc