Why Lombok’s Getter/Setter Breaks MyBatis and EasyExcel – Causes and Fixes

When using Lombok in a Java project, the generated getter/setter methods can clash with frameworks that rely on the JavaBeans naming convention.

Setter-Getter Method Pitfall

Problem Discovery

When inserting an entity with MyBatis, the enum field nMetaType was always stored as null, even though the object contained a value.

@Data
public class NMetaVerify {
    private NMetaType nMetaType;
    private Long id;
    // ... other fields
}

Debugging showed the field had data before the insert, but MyBatis obtained the property name via reflection using the getter method, which Lombok generated as getNMetaType (capital N), while MyBatis expects getnMetaType.

Cause

Lombok follows a rule where a property whose first two letters are lowercase‑uppercase (e.g., nMetaType) gets getters/setters with the second letter capitalized, diverging from the JavaBeans convention used by MyBatis, IDEs, and the official specification.

// Lombok‑generated
public NMetaType getNMetaType() { ... }
public void setNMetaType(NMetaType nMetaType) { ... }

// Standard JavaBeans
public NMetaType getnMetaType() { return nMetaType; }
public void setnMetaType(NMetaType nMetaType) { this.nMetaType = nMetaType; }

The MyBatis PropertyNamer.methodToProperty logic (excerpt) shows how it derives the property name from method names.

public static String methodToProperty(String name) {
    if (name.startsWith("is")) { name = name.substring(2); }
    else if (name.startsWith("get") || name.startsWith("set")) { name = name.substring(3); }
    // ... handling of single‑letter names and lower‑casing ...
    return name;
}

Solution

Rename the field so that the first two letters are both lowercase (e.g., nmMetaType) or avoid the special case.

Manually write proper getters/setters for such fields, or let the IDE generate them instead of Lombok.

@Accessor(chain = true) Annotation Issue

Problem Discovery

When exporting objects with EasyExcel, newly added DTOs annotated with @Accessor(chain = true) failed to export correctly.

new UserDto()
    .setUserName("")
    .setAge(10)
    .setBirthday(new Date());

Cause

EasyExcel relies on CGLIB and Java’s Introspector to discover bean properties. The introspection code only treats methods that return void as setters, so chainable setters that return the object break the detection.

// CGLIB BeanMap usage
BeanMap.create(resultModel).putAll(map);

// Introspector snippet
if (void.class.equals(resultType) && name.startsWith(SET_PREFIX)) {
    pd = new PropertyDescriptor(beanClass, name.substring(3), null, method);
}

Solution

Remove the @Accessor(chain = true) annotation.

Await an update from EasyExcel to support non‑void returning setters, or replace the underlying CGLIB usage.