如何在Java中移除TCP传输的压力传感器消息冗余部分并提取JSON数据

Got it, let's break down how to solve this problem—you need to strip out the redundant HTTP request headers from your TCP-received message and extract only the JSON sensor data. Here's a step-by-step solution with code examples:

Approach #

The key here is to separate the HTTP header noise from the JSON payload. We have two reliable ways to do this, depending on how your message is formatted:

1. Use HTTP Protocol Separator: Standard POST requests separate headers from the body with a blank line (\r\n\r\n). This is the most accurate method if your message follows HTTP specs.
2. Locate JSON Boundaries: If the header and JSON are directly concatenated without the standard separator, we can find the first { and last } to extract the full JSON block (since JSON is always wrapped in outer curly braces).

We'll also need to handle the HTML-escaped double quotes (") in your JSON data—replace them with regular double quotes so JSON parsers can read the data correctly.

Java Code Implementation #

Step 1: Extract and Clean the JSON String #

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class SensorMessageParser {

    public static String extractAndCleanJson(String rawTcpMessage) {
        String jsonContent = null;

        // First, try using the standard HTTP header-body separator (\r\n\r\n)
        String httpSeparator = "\r\n\r\n";
        int separatorIndex = rawTcpMessage.indexOf(httpSeparator);
        if (separatorIndex != -1) {
            jsonContent = rawTcpMessage.substring(separatorIndex + httpSeparator.length());
        } else {
            // Fallback: Find the first { and last } to capture the full JSON block
            int startJson = rawTcpMessage.indexOf("{");
            int endJson = rawTcpMessage.lastIndexOf("}");
            if (startJson != -1 && endJson != -1 && startJson < endJson) {
                jsonContent = rawTcpMessage.substring(startJson, endJson + 1);
            } else {
                throw new IllegalArgumentException("Invalid message: No valid JSON payload found");
            }
        }

        // Replace HTML-escaped quotes with regular double quotes
        return jsonContent.replaceAll("&quot;", "\"");
    }

    public static void main(String[] args) {
        // Example raw message from your sensor
        String rawMessage = "POST /V1.0/data.aspx HTTP/1.1 Host: 124.43.5.212 User-Agent: RT-Thread HTTP Agent Connection: Keep-Alive Content-Length: 4349{ &quot;device&quot;: &quot;0305170025&quot;, &quot;Business&quot;: &quot;0305170025&quot;, &quot;version&quot;: &quot;V1.0&quot;, &quot;session&quot;: 1631171130, &quot;command&quot;: &quot;send_server_measure&quot;, &quot;content&quot;: { &quot;measure&quot;: [ { &quot;name&quot;: &quot;press&quot;, &quot;datatype&quot;: &quot;float&quot;, &quot;content&quot;: [ { &quot;t&quot;: 1631169540, &quot;v&quot;: 9901 }, { &quot;t&quot;: 1631169550, &quot;v&quot;: 9901 }, { &quot;t&quot;: 1631169560, &quot;v&quot;: 9901 }, { &quot;t&quot;: 1631171130, &quot;v&quot;: 9901 } ] } ] } }";
        
        try {
            String cleanedJson = extractAndCleanJson(rawMessage);
            System.out.println("Extracted and cleaned JSON:\n" + cleanedJson);
            // Now you can parse this JSON into a Java object
        } catch (IllegalArgumentException e) {
            System.err.println("Error parsing message: " + e.getMessage());
        }
    }
}

Step 2: Parse the Cleaned JSON into a Java Object #

Once you have the cleaned JSON, use a library like Jackson or Gson to convert it into a strongly-typed Java object for easier processing. Here's an example with Jackson:

First, add the Jackson dependency to your pom.xml (Maven) or build.gradle (Gradle):

<!-- Maven -->
<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.15.2</version>
</dependency>

Then create the corresponding model classes:

import java.util.List;

public class SensorData {
    private String device;
    private String Business;
    private String version;
    private long session;
    private String command;
    private Content content;

    // Getters and Setters
    public String getDevice() { return device; }
    public void setDevice(String device) { this.device = device; }
    public String getBusiness() { return Business; }
    public void setBusiness(String business) { Business = business; }
    public String getVersion() { return version; }
    public void setVersion(String version) { this.version = version; }
    public long getSession() { return session; }
    public void setSession(long session) { this.session = session; }
    public String getCommand() { return command; }
    public void setCommand(String command) { this.command = command; }
    public Content getContent() { return content; }
    public void setContent(Content content) { this.content = content; }

    public static class Content {
        private List<Measure> measure;

        // Getters and Setters
        public List<Measure> getMeasure() { return measure; }
        public void setMeasure(List<Measure> measure) { this.measure = measure; }

        public static class Measure {
            private String name;
            private String datatype;
            private List<DataPoint> content;

            // Getters and Setters
            public String getName() { return name; }
            public void setName(String name) { this.name = name; }
            public String getDatatype() { return datatype; }
            public void setDatatype(String datatype) { this.datatype = datatype; }
            public List<DataPoint> getContent() { return content; }
            public void setContent(List<DataPoint> content) { this.content = content; }

            public static class DataPoint {
                private long t;
                private int v;

                // Getters and Setters
                public long getT() { return t; }
                public void setT(long t) { this.t = t; }
                public int getV() { return v; }
                public void setV(int v) { this.v = v; }
            }
        }
    }
}

Now parse the JSON into the model:

import com.fasterxml.jackson.databind.ObjectMapper;

public class JsonParser {
    public static void main(String[] args) {
        String cleanedJson = // The cleaned JSON from extractAndCleanJson()
        ObjectMapper objectMapper = new ObjectMapper();
        try {
            SensorData sensorData = objectMapper.readValue(cleanedJson, SensorData.class);
            // Access the sensor data
            System.out.println("Device ID: " + sensorData.getDevice());
            System.out.println("First pressure reading: " + sensorData.getContent().getMeasure().get(0).getContent().get(0).getV());
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

Notes #

• Always prefer the HTTP separator method if possible—it's more reliable for messages that follow HTTP standards.
• The fallback method using { and } works if the header doesn't contain any curly braces (which is true for standard HTTP headers).
• Make sure to handle exceptions appropriately (e.g., invalid message formats, JSON parsing errors) in your production code.

内容的提问来源于stack exchange，提问作者Yushantha chathuranga