code4craft/webmagic · error · IllegalArgumentException

illegal encoding

Error message

illegal encoding 

What it means

HttpRequestBody.json() encodes the JSON string with the given charset; if the charset name is not supported on the JVM, UnsupportedEncodingException is caught and rethrown as IllegalArgumentException('illegal encoding ' + encoding).

Solutions

1. Use a canonical constant: StandardCharsets.UTF_8.name()
2. Normalize/trim the charset and validate with Charset.isSupported(encoding) before calling
3. Fall back to UTF-8 when the encoding is unknown

Example fix

// before
HttpRequestBody.json(json, "utf_8");
// after
String encoding = "utf_8";
if (!Charset.isSupported(encoding)) encoding = StandardCharsets.UTF_8.name();
HttpRequestBody.json(json, encoding);

if (!java.nio.charset.Charset.isSupported(encoding)) encoding = java.nio.charset.StandardCharsets.UTF_8.name();

try { HttpRequestBody.json(json, encoding); } catch (IllegalArgumentException e) { HttpRequestBody.json(json, "UTF-8"); }

When it happens

Trigger: Calling HttpRequestBody.json(json, "utf8") or any misspelled charset ('utf-8 ' with trailing space, 'utf_8'); charset not present in the JVM's supported list.

Common situations: Hardcoding charset names from config or headers without canonicalization; typos like 'utf8' vs 'UTF-8' on strict JVM configurations; reading encoding from an HTTP Content-Type header.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

• threadNum should be more than one!
• emptySleepTime should be more than zero!
• task or site can not be null
• Illegal HTTP Method
• language and script must not be null!

AI-assisted analysis of code4craft/webmagic@67816a19d6 (2026-09-08). Data as JSON: /api/errors/91cdca7e7468528c. Report an issue: GitHub.

Appendix: source

Thrown at webmagic-core/src/main/java/us/codecraft/webmagic/model/HttpRequestBody.java:71

    }

    public void setBody(byte[] body) {
        this.body = body;
    }

    public void setContentType(String contentType) {
        this.contentType = contentType;
    }

    public void setEncoding(String encoding) {
        this.encoding = encoding;
    }

    public static HttpRequestBody json(String json, String encoding) {
        try {
            return new HttpRequestBody(json.getBytes(encoding), ContentType.JSON, encoding);
        } catch (UnsupportedEncodingException e) {
            throw new IllegalArgumentException("illegal encoding " + encoding, e);
        }
    }

    public static HttpRequestBody xml(String xml, String encoding) {
        try {
            return new HttpRequestBody(xml.getBytes(encoding), ContentType.XML, encoding);
        } catch (UnsupportedEncodingException e) {
            throw new IllegalArgumentException("illegal encoding " + encoding, e);
        }
    }

    public static HttpRequestBody custom(byte[] body, String contentType, String encoding) {
        return new HttpRequestBody(body, contentType, encoding);
    }

    public static HttpRequestBody form(Map<String,Object> params, String encoding){
        List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(params.size());
        for (Map.Entry<String, Object> entry : params.entrySet()) {

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